C-NRLF 


SHOP 
INSTALLATION 

AND 

MAINTENANCE 


GREENE 


Vocational  Education 


From  the  collection  of  the 

o  Prelinger 

I.H  a 

JJibrary 


San  Francisco,  California 
2006 


SCHOOL  SHOP 

INSTALLATION  AND 

MAINTENANCE 


L.  S.  GREENE,  M.S. 

Stale  Supervisor  Industrial  Education,  Florida 
Professor  Industrial  Education,  University  of  Florida 

Formerly 

Assistant  Professor  of  Industrial  Education, 
University  of  Wisconsin 


THE  MANUAL  ARTS  PRESS 
PEORIA,  ILLINOIS 


<0 


Copyright,  1922 
L.  S.  GREENE 

I2D22 


Printed  in  the  United  Slates  of  America 


PREFACE 

• 

THE  author  has  observed  that  among  teachers  of  shop   sub- 
jects  there   is   a  noticeable  lack  of  ability  when  it  becomes 
their  duty  to  solve  problems  of  school  shop  planning,  installation 
and  maintenance. 

The  fundamental  reason  for  this  deficiency  is,  perhaps,  that, 
altho  there  are  numerous  technical  books  and  magazine  articles 
dealing  with  such  problems,  they  are  written  primarily  for  the 
engineer  and  do  not  provide  readily  the  comparatively  simple, 
yet  essential  information  needed  by  the  shop  teacher  when  it 
becomes  his  duty  and  privilege  to  plan,  install  and  keep  in  order 
school  shop  equipment. 

The  purpose  of  this  book  is  therefore  two-fold.  An  attempt 
has  been  made  to  present  in  simple  language  and  readily  usable 
form,  information,  rules  and  methods  that  (1)  will  constitute  a 
handbook  for  teachers  for  use  in  solving  these  problems  of  equip- 
ment and  maintenance,  and  (2)  will  be  a  text  for  use  in  normal 
courses  in  which  manual  arts  and  vocational  teachers  are  trained. 

While  the  material  presented  in  these  notes  may  be  of  greatest 
use  to  shop  teachers  as  a  handbook  and  to  teachers  of  vocational 
teacher-training  classes,  these  two  purposes  do  not  limit  its  use. 
For  instance,  pupils  in  many  vocational  classes  should  know  how 
to  take  care  of  belting  properly,  how  to  babbitt  a  bearing,  how  to 
fit  circular  saws,  braze  bandsaws,  etc.,  and  in  this  sense  this  book 
can  be  used  as  a  text  and  reference  book  by  the  students.  Because 
of  the  direct  method  of  presenting  the  subject  matter,  the  book 
should  also  prove  valuable  to  apprentices  and  mechanics. 

The  author  wishes  to  express  his  indebtedness  to  Prof.  F.  D. 
Crawshaw  for  timely  suggestions.  The  author's  wife  and  associate 
teachers  have  also  been  of  much  assistance. 

The  illustrations  are  the  work  of  the  author. 
UNIVERSITY  OF  WISCONSIN,  1921  L.  S.  G. 


661942 


CONTENTS 

PART  ONE— INSTALLATION 

CHAPTER  I.     POWER  TRANSMISSION  IN  A  SCHOOL  SHOP  .      .       7 

1.  Individual  vs.  group  drive;  2.  Advantages  of  individual  drive; 
3.  Advantages  of  group  drive;  4.  Selection  of  shafting;  5.  Speeds 
of  line  shafts;  6.  Rules  for  determining  speeds;  7.  Position  of 
shafting;  8.  Hangers;  9.  First  alignment,  hangers  and  shafting; 
10.  Fastening  hangers;  11.  Second  alignment;  12.  Set  collars; 
13.  Aligning  pulleys;  14.  Pulleys  and  couplings;  15.  Placing 
pulleys;  16.  Shaft  couplings;  17.  Rules  for  finding  sizes  and 
speeds  of  pulleys. 

CHAPTER  II.     MOTORS  AND  CURRENTS 24 

18.  General  considerations;  19.  Two  types  of  work;  20.  Ad- 
vantages of  A.  C.  motors;  21.  Advantages  of  D.  C.  motors; 
22.  Data  required  in  determining  the  choice  of  motor;  23.  Plan- 
ning for  motor  drive;  24.  Installation  of  electric  motors;  25. 
Care  of  motors. 

CHAPTER  III.    INSTALLATION  OF  METALWORKING  EQUIPMENT    28 

26.  General  considerations;    27.  Planer;    28.  Lathes;    29.  Drill 
press;  30.  Milling  machine;  31.  Shaper;  32.  Forge;  33.  Anvil; 
'34.  Blower. 

CHAPTER  IV.     INSTALLATION  OF  WOODWORKING  EQUIPMENT    33 

35.  General  considerations;  36.  Speeds  of  various  machines; 
37.  Emery  wheel  speeds;  38.  Circular-saw  speeds;  39.  Horse- 
power required  for  woodworking  machines;  40.  Other  factors  to 
consider. 

PART  TWO— MAINTENANCE 

CHAPTER  V.     FITTING  EDGE  TOOLS    .      .      .      .      .      .      .39 

41.  Plane  irons;  42.  Chisels;  43.  Turning  tools;  44.  The 
draw-knife;  45.  Spokeshave  blades;  46.  The  outside  gouge; 
47.  The  inside  gouge;  48.  Cabinet  scrapers;  49.  Planer  and 
jointer  knives. 

CHAPTER  VI.     FITTING  SAWS 47 

50.  Hand  rip-saw;  51.  Hand  crosscut-saw;  52.  Keyhole-saw; 
53.  Miter-  and  back-saws;  54.  Band-saws;  55,  Circular  rip- 
saws; 56.  Circular  crosscut-saws. 

5 


6  CONTENTS 

CHAPTER  VII.     BRAZING  BAND  SAWS.       ......     57 

57.  Brazing. 

CHAPTER  VIII.     BELTING .     61 

58.  Belt  comparisons;    59.  Choosing  a  belt;   60.  Care  of  belts; 
61.  Applying  belts  to  pulleys;    62.  Joining  belts;    63.  Lacing 
2"  to  4"  belt  with  rawhide;  64.  Other  rawhide  laces;  65.  Heavy 
work  on  large  pulleys;    66.  Lacing  with  wire;    67.  Patent  fas- 
teners;   68.  Cemented    splices;    69.  Don'ts;    70.  To   find    the 
horse-power  which  a  belt  will  transmit;  71.  To  find  width  of  belt 
required    for  a  given    horse-power;    72.  With  horse-power  and 
width  of  belting  given,  to  find  diameter  of  driven  pulley  required; 
73.  To  find  the  length  of  belt  wanted;  74.  To  find  the  horse-power 
of  a  driving  pulley. 

CHAPTER  IX.     BABBITTING      ..'.-.     . 77 

75.  Babbitt  metal;  76.  Preparing  to  pour  babbitt  metal;  77. 
Alignment  of  the  shaft;  78.  Preparing  the  shaft;  79.  Damming 
up  the  box;  80.  Melting  the  metal;  81.  Pouring  the  metal;  82. 
Scraping  the  babbitt. 

CHAPTER  X.     ADJUSTMENTS  OF  WOODWORKING  MACHINES  .     88 

83.  The  circular-saw;  84.  The  jointer;  85.  The  surfacer;  86. 
The  mortiser;  87.  The  band-saw;  88.  The  lathe;  89.  Play  in 
bearings. 

APPENDIX. 95 

ORGANIZATION  OF  THE  PRECEDING  MATERIAL  FOR  TEACHING  PURPOSES. 


PART  ONE— INSTALLATION 

CHAPTER  I 

POWER  TRANSMISSION  IN  A  SCHOOL  SHOP 

1.  Individual    vs.    Group    Drive. — There    are    two    common 
methods  of  driving  machines.    One  consists  in  connecting  the  source 
of  power  to  a  line  shaft  from  which  the  individual  machines  re- 
ceive their  power  by  means  of  belting  and  pulleys.    This  system  is 
called  group  drive.     The  other  method  consists  in  connecting  a 
machine  directly  to  a  source  of  power  and  is  called  individual  drive. 
In  the  second  case,  an  electric  motor  is  generally  used  for  the  power 
and,  in  the  following  discussion  of  individual  drive,  such  power 
will  be  assumed. 

It  is  not  necessary,  of  course,  that  the  machines  be  driven  by 
either  method  alone  for  the  nature  of  the  work  to  be  done  or  the 
equipment  to  be  used  may  make  it  desirable  to  combine  these 
two  methods  in  the  same  shop  so  that  part  of  the  equipment  is 
run  as  group  and  part  as  individual  drive.  Determination  of  the 
method  to  be  used  should  come  only  after  careful  consideration  has 
has  been  given  to  the  advantage  of  each  type  and  after  a  thought- 
ful survey  has  been  made  of  the  machines  to  be  driven,  the  work 
to  be  done  on  them,  and  the  comparative  amount  of  time  that 
each  will  be  in  use. 

2.  Advantages  of  Individual  Drive. — In  the  individual  drive 
type  of  power  transmission,  there  is  often  obtained  a  decided  saving 
in  the  amount  of  floor  space  necessary  for  different  machines. 
It  is  not  necessary  to  locate  the  machines  in  a  line  or  in  a  certain 
order  or  so  that  they  will  face  the  same  way.    This  often  permits 
of  better  aisle  arrangements  and  better  use  of  daylight  for  the 
operation  of  the  machines.     The  absence  of  complex  overhead 
shafting,  pulleys  and  speeding  belts  allows  of  better  lighting, 

1    7 


8  SCHOOL  SHOP  INSTALLATION 

avoids  collections  of  dust  and  oil  which  fall  down  on  the  machines 
and  the  work,  and  removes  much  of  the  dangers  attendant  upon 
an  industrial  shop  because  of  fast  turning  belts  and  pulleys. 

If  the  work  being  done  is  intermittent  in  nature  and  the 
machines  are  not  all  running  all  the  time  or  at  full  capacity  all 
the  time,  as  is  the  case  in  nearly  all  school  shops,  then  there  is  a 
saving  in  the  cost  of  operation  and  upkeep  of  machines,  shafting 
and  belting.  There  are  fewer  delays  of  all  machines  by  breakdown 
of  belts,  loosening  of  pulleys,  etc.  In  a  wood  shop  or  a  metal 
shop,  it  is  often  desirable  to  run  the  band-saw,  drill-press  or  some 
other  machine  without  necessitating  the  running  of  a  complete 
line  shaft,  and  possibly  other  machines  with  it,  and  this  is  not 
necessary  if  the  individual  type  of  transmission  is  used.  Machines 
are  made  more  portable  by  individual  drive  and  more  variation 
of  speed  for  the  work  to  be  done  is  possible.  Some  machines  can 
function  properly  with  the  motor  connected  direct  to  the  main 
shaft,  as  in  the  case  of  the  band-saw  or  small  circular-saw,  and  thus 
the  annoyances  obtained  from  the  slipping  of  belts  is  avoided. 
The  energy  of  the  teacher  is  conserved  because  of  the  fewer  repairs 
necessary  with  the  result  that  more  efficient  instruction  should 
obtain. 

The  following  reasons  why  individual  motor  driven  machines 
are  preferable  in  schools  are  given  by  The  Oliver  Machinery  Co., 
Grand  Rapids,  Mich. 

1.  Because  they  are  more  sanitary. 

a.  Less  belting  causes  less  dust. 

b.  Less  belting  affords  more  light. 

c.  No  oil  drippings  from  overhead  bearings. 

2.  Because  they  are  safer. 

a.  No  belting  to  get  tangled  in. 

b.  No  belts  to  break  and  fall  down. 

c.  No  overhead  shafting  or  other  material  to  be  pulled  down. 

3.  Because  they  are  less  noisy. 

a.  No  belts  or  shafting  to  create  noise. 

b.  Only  machines  in  actual  use  make  any  noise  at  all. 

4.  Because  they  require   less   attention  from  instructor,   assuring 

better  instruction. 

a.  Less  parts  to  adjust. 

b.  Fewer  bearings  to  lubricate. 

c.  Fewer  belts  to  keep  tight  and  in  shape. 


POWER  TRANSMISSION  9 

d.     Fewer  disputes  with  students  because  they  have  less  chance  for 
mischief. 

5.  Because  they  individualize  each  student's  operations. 

a.  Students  become  masters  of  their  own  realm. 

b.  No  time  lost  because  of  another's  carelessness. 

c.  Better  discipline  is  possible  because  of  less  opportunity  for 
intercommunication. 

6.  Because  of  less  wear  and  tear — upkeep  is  cheaper. 

a.  No  unnecessary  running  parts — belts,  shafts,  bearings — hence 
fewer  repairs. 

b.  Machines  will  last  longer  because: 

(1)  During  class  hours,  only  machines  in  actual  use  are  running. 

(2)  At  odd  times  such  as  after  school  and  on  Saturdays,  only 
machines  needed  are  run. 

7.  Because  operating  cost  is  less. 

a.  Less  oil,  waste  and  belting  is  used. 

b.  Less  current  used  because  power  required  merely  when  doing 
actual  work. 

8.  Because  the  sytem  is  more  flexible — saves  room. 

a.  Machines  may  be  located  as  suits  the  room  and  utility,  without 
regard  to  direction  of  shafting. 

b.  Future  additions  or  alterations  are  more  easily  performed. 

3.  Advantages  of  Group  Drive. — The  initial  cost  of  group 
drive  is  often  much  less  than  that  of  individual  drive  and  with 
certain  machines  or  groups  of  machines  this  method  might  be 
more  acceptable  as  far  as  cost  of  operation  is  concerned.  This  is 
plain  in  the  case  of  a  number  of  wood  lathes,  driven  from  one  line 
shaft,  where  the  total  horse-power  needed  at  any  one  time  is  less 
than  the  sum  total  of  the  maximum  horse-power  of  the  several 
machines.  While  each  machine  needs,  under  certain  conditions, 
its  maximum  horse-power,  yet  very  seldom,  and  perhaps  never, 
would  conditions  be  such  that  all  machines  would  be  using  their 
maximum  horse-power  at  the  same  time.  It  is  safe  to  assume  that 
the  power  necessary  to  drive  this  line  shaft  under  these  conditions 
would  be  from  40  per  cent,  to  80  per  cent,  of  the  sum  total  of  the 
maximum  horse-power  of  all  lathes  on  the  shaft.  If  these  lathes 
were  driven  by  individual  motors,  a  greater  total  amount  of  horse- 
power would  have  to  be  provided  to  drive  them.  In  the  case  of 
machines,  like  the  lathes  mentioned  above,  where  nearly  all,  or  all, 
are  driven  at  the  same  time,  there  is  economy  in  the  group  drive. 
Wherever  the  machines  are  small  and  require  little  power,  or  where 
the  initial  cost  of  individual  drive  might  over-balance  the  operative 


10  SCHOOL  SHOP  INSTALLATION 

economies  of  the  same  drive,  it  might  be  advisable  to  install  group 
drive  transmission. 

4.  Selection  of  Shafting. — Cold-rolled  steel  is  generally  used 
for  shafting  up  to  3"  in  diameter  and  is  considered  to  be  about 
15%  stronger  than  turned  steel  shafting.  It  is  round  and  straight 
and  needs  no  turning  unless  key-ways  are  to  be  cut  in  it,  in  which 
case  the  tension  on  the  surface  is  relieved,  and  it  may  take  a  form 
not  perfectly  round. 

In  selecting  shafting,  one  should  consider  not  only  immediate 
needs  but  also  possible  needs  of  the  future;  such  as  adding  to  the 
amount  or  the  size  of  the  machinery  that  is  to  be  driven  by  the 
shafting,  increasing  the  size  of  the  driving  motor,  or  the  erection  of 
secondary  shafting,  (i.  e.,  another  shaft  to  be  driven  by  the  shaft 
receiving  the  power  by  being  belted  to  it),  for  the  choice  of  the  size 
of  a  shaft  should  depend  upon  two  things  (1)  its  ability  to  withstand 
twisting  forces  when  it  receives  and  transmits  power,  and  (2) 
its  ability  to  remain  stiff  or  to  resist  bending  forces  due  to  the 
weight  of  the  shaft  itself,  weight  of  pulleys,  pull  of  belts  and  dis- 
tance apart  of  hangers.  Should  more  demands  upon  the  shafting 
be  expected  in  the  future,  then  it  is  wise  to  consider  these  probable 
demands  when  making  a  choice  of  shafting,  for  thus  a  saving  in 
time,  annoyance  and  money  may  often  be  effected. 

As  it  is  not  possible  to  know  exactly  what  additional  pulleys, 
machines  and  power  will  be  needed  in  the  future  or  what  shifting 
and  changing  of  machines  and  pulleys  will  take  place,  it  is  im- 
possible to  determine  exactly  the  size  of  the  shaft.  Undoubtedly 
the  best  policy  would  be  to  play  safe  by  choosing  a  shaft  slightly 
larger  than  apparently  seems  necessary,  according  to  tables  that 
will  follow,  for  the  extra  cost  will  be  justified  as  a  precaution 
against  a  possibility  of  adding  extra  hangers,  new  bearings,  or 
even  a  larger  shaft  at  a  later  date,  any  of  which  would  probably 
cost  more  than  an  extra  size  of  shafting  when  first  installed. 

Another  point  to  think  about  and  investigate  is  whether  the 
immediate  demands  upon  the  shaft  are  what  might  be  called  normal 
or  usual  demands,  i.  e.,  hangers  a  usual  distance  apart,  the  pull 


POWER  TRANSMISSION  11 

of  the  belts  in  such  a  direction  as  to  offset  one  another,  pulleys 
close  to  hangers,  etc.  If  the  condition  as  regards  these  points 
is  such  as  to  increase  the  bending  tendency  of  the  shaft  then  the 
shafting  should  be  larger  to  make  up  for  this  tendency  even  if 
the  power  to  be  received  or  transmitted  does  not  seem  to  require  a 
larger  shaft.  The  tables  which  follow  are  guides  only  and  not  hard 
and  fast  rules  and  one  should  bear  this  in  mind  when  using  them. 

Where  there  is  a  long  stretch  of  shafting  and  where  the  de- 
mands upon  the  shaft,  at  the  far  end  away  from  where  the  power 
is  received  or  transmitted  to  secondary  shafting,  are  not  so  heavy 
as  at  the  other  end,  there  is  some  economy  in  reducing  the  size  of 
the  shafting  at  this  far  end.  This  can  be  done  at  a  coupling  by 
reducing  the  size  of  the  larger  shaft  to  that  of  the  smaller  shaft  so 
that  both  of  them  fit  the  same  coupling. 

Weight  for  weight  a  hollow  shaft  is  stronger  than  a  solid  one, 
but  where  the  diameters  are  the  same  the  solid  one  is  the  stronger. 
A  shaft  will  deliver  more  power  at  fast  speed  than  at  slow,  and  the 
diameter  required  to  deliver  a  certain  horse-power  at  fast  speed 
is  less  than  that  required  for  the  same  horse-power  at  slow  speed. 
A  shaft,  equal  in  diameter  to  another  but  running  twice  as  fast, 
will  transmit  twice  as  much  power,  or  in  other  words,  the  horse- 
power is  directly  proportional  to  the  number  of  revolutions  per 
minute  of  the  shaft. 

5.  Speeds  of  Line  Shafts. — For  machine  shops,  120  to   240 
R.  P.  M. 

For  woodworking  shops,  250  to  300  R.  P.  M. 
(R.  P.  M.  means  revolutions  per  minute.) 

6.  Rules  for  Determining  Horse-Power. — A  shaft  which  carries 
a  receiving  pulley  or  a  transmitting  pulley  for  driving  another  line 
should  be  considered  a  prime  mover  or  head  shaft  when  the  rules 
which  are  to  follow  are  used. 

To  determine  the  horse-power  (H.  P.)  transmitted  by  cold-rolled 
steel  shafting  at  different  speeds  as  prime  movers  or  head  shafts 
carrying  the  main  driving  pulley  and  well  supported  by  bearings 
use  the  following  formula: 


12 


SCHOOL  SHOP  INSTALLATION 


H.  P.= 


100 


where  d  =  diameter  of  shaft  in  inches,  R  =  R.  P.  M. 


of  the  shaft  and  H.  P.  =  horse-power  transmitted. 

As  an  example,  determine  the  horse-power  transmitted  by  a 
shaft  2"  in  dia.  running  300  R.  P.  M.  Using  the  formula  above  and 
substituting  for  the  letters  the  figures  given  in  the  example  we 


getH.  P.= 


2X2X2X300 
100 


=  24. 


Below  is  a  table  giving  various  combinations  ofH.  P.,  R.  P.  M., 
and  diameters. 

Applications  of  the  Above  Formula 


Dia.  of  Shaft 


Horse  Power 


100 
R.P.M. 


200 
R.  P.  M. 


300 
R.  P.  M. 


3.4 

3.8 

4.3 

4.8 
5.4 

1%.. 5.9 

6.6 

1% 7.3 

2 8.0 

2% 8.8 

9.6 
2% 10.5 

11.4 

2% 12.4 

13.4 

2% 14-5 

15.6 

2% 16.8 

18-1 

2% 19-4 


6.7 
7.6 
8.6 
9.6 
10.7 
11.9 
13.1 
14.5 
16'.  0 
17.6 
19.2 
21 
23 
25 
27 
29 
31 
34 
36 
39 


10.1 

11.4 

12.8 

14.4 

16.1 

17.8 

19.7 

22 

24 

26 

29 

31 

34 

37 

40 

43 

47 

50 

54 

58 


POWER  TRANSMISSION 


13 


Hotse  Power 

Dia.  of  Shaft 

100 
R.  P.  M. 

200 
R.  P.  M. 

300 
R.  P.  M. 

2^ 

21 

41 

62 

213<fi 

22 

44 

67 

2yg  

2%    . 

24 
25 

48 
51 

72 
76 

3.  . 

27 

54 

81 

To  illustrate  the  use  of  the  above  table,  let  us  assume  it  is 
desired  to  know  the  H.  P.  transmitted  by  a  2"  cold-rolled  steel 
shaft  running  at  200  R.  P.  M.  as  a  prime  mover.  By  running  the 
finger  down  the  200  column  to  a  point  opposite  the  figure  2  in  the 
dia.  column  we  find  16  as  the  H.  P.  given.  Similarily,  if  it  is  de- 
sired to  know  the  proper  size  of  cold-rolled  steel  shafting  to  run 
at  300  R.  P.  M.  as  a  prime  mover  to  deliver  25  H.  P.,  we  run  the 
finger  down  the  300  column  in  search  of  figure  25  and  find  that  the 
nearest  figure  would  be  24  or  26  and  we  choose  the  latter  to  be 
Fafe  and  find  that  the  figure  in  the  dia.  column  opposite  is  2j/fj}",  the 
dia.  required.  Or,  let  us  find  the  H.  P.  for  cold-rolled  steel  shafting 
2-^6"  in  dia.  to  run  250  R.  P.  M.  as  a  prime  mover.  Reference 
to  the  table  will  show  that  no  250  column  is  given  but,  in 
the  200  column  for  this  dia.  we  find  21  as  the  horse-power  and 
in  the  300  column  we  find  31  as  the  horse-power  and  as  250 
R.  P.  M.  is  half  way  between  200  and  300  R.  P.  M.  we  accept 
the  figure  26,  which  is  half  way  between  21  and  31,  as  the  H.  P. 
required. 

The  above  table  is  accurate  only  for  cold  rolled  steel  shafting.  In 
order  to  make  it  of  more  use  the  following  rules  are  given. 

1 — For  H.  P.  transmitted  by  turned  steel  shafts  as  prime 
movers,  multiply  the  figures  in  the  table  above  that  represent 
H.  P.  by  0.8. 

2 — For  shafts  as  second  movers  or  line  shafts  with  bearings  8  ft., 
apart,  multiply  by  1.43  for  cold-rolled  and  by  1.11  for  turned 
steel  shafts  to  get  the  H.  P.  safely  transmitted. 


14  SCHOOL  SHOP  INSTALLATION 

3 — For  simply  transmitting  power  (short  counter-shafts,  etc.) 
with  bearings  8  ft.  apart  or  less,  multiply  by  2.0  for  cold-rolled 
and  by  2.5  for  turned  steel  shafting. 

As  an  example  of  the  above  let  us  assume  that  we  wish  to  know 
the  H.  P.  that  is  safely  transmitted  by  a  2j^"  turned  steel  line  shaft 
with  bearings  8  ft.  apart  running  at  200  R.  P.  M.  Referring  to  the 
table,  we  run  the  finger  down  the  200  column  of  figures  to  the 
number  in  this  column  opposite  2j^"  dia.  and  we  find  that  31  is 
the  horse-power  given.  This  31  H.  P.  represents  the  H.  P.  per- 
missible with  cold  rolled  steel  shafting  as  a  prime  mover  but  as  we 
wish  to  know  what  H.  P.  is  advisable  with  turned  steel  shafting  as 
a  line  shaft  we  refer  to  rule  2  above.  This  rule  reads  to  multiply 
the  31  H.  P.,  gained  from  the  table,  by  1.11  which  gives  us  31xl.ll 
=  34  H.  P.  Rules  1  and  3  can  be  used  similarly. 

7.  Position  of  Shafting. — Shafting  may  be  fastened  to  the 
wall,  to  the  ceiling  or  to  the  floor.  The  greatest  economy  of  space 
is  obtained  in  most  cases  by  fastening  it  to  the  ceiling.  When 
fastened  to  the  wall  or  floor  the  arrangement  of  the  belts  and 
pulleys  makes  them  inconvenient  and  dangerous  if  an  attempt  is 
made  to  use  the  floor  space  close  to  them.  Shafting  on  the  floor 
should  be  well  guarded  by  fences  or  railings.  The  number  of 
machines  that  can  be  driven  from  shafting  elsewhere  than  on  the 
ceiling  is  limited.  The  belts  from  lathes,  for  instance,  must  run 
to  pulleys  above  the  lathes. 

The  distance  apart  of  shafts,  counter-shafts,  and  connected 
pulleys  will  depend  upon  (1)  physical  limitations  and  those  of 
convenience,  and  (2)  width  of  the  belt  to  be  used  and  the  corre- 
sponding work  expected  of  it.  The  necessary  arrangement  of  the 
shafting  and  machinery  may  be  such  as  to  make  other  considera- 
tions quite  dependent  upon  their  arrangement  but,  if  possible, 
the  distance  between  the  pulleys  should  be  such  as  to  allow  of  a 
gentle  sag  to  the  belt  when  in  motion.  This  allows  a  belt  to  have 
better  contact  with  the  pulleys  and  requires  less  tension  on  the 
belt  for  the  same  amount  of  horse-power.  Increased  tension  means 
increased  strains  in  the  belt  and  added  wear  and  friction  in  the 


POWER  TRANSMISSION  15 

bearings.  About  2"  of  sag  in  narrow  belts  and  from  3  to  4"  in  wide 
belts  is  sufficient. 

Where  it  can  be  avoided,  connected  pulleys  should  not  be  placed 
one  directly  above  the  other  for  then  only  a  minimum  contact 
with  the  belt  is  obtained,  and  more  tension  in  the  belt  is  required 
to  deliver  a  certain  amount  of  horse-power  than  if  the  pulleys  con- 
nected more  nearly  horizontal. 

8.  Hangers. — There  are  three  common  types  of  hangers  em- 
ployed for  the  suspension  of  shafting,  viz. :  drop,  post  and  wall  ex- 
tension hangers.  Each  type  varies  in  that  some  are  rigid  and  not 
easily  adjusted  while  others  have  varying  methods  of  adjustment. 

The  best  types  of  drop  hangers  are  those  which  have  screw 
adjustments.  Two  screws  adjust  the  up  and  down  movement  and 
two  others  adjust  the  lateral  or  side  movement.  These  screws 
aid  materially  in  securing  a  quick  and  accurate  aligning  of  the 
shafts.  Other  types  have  screws  for  adjusting  the  vertical  move- 
ment of  the  bearing  only.  A  refinement  of  the  former  type  is  the 
substituting  of  a  roller  bearing  which  minimizes  the  friction  and 
wear,  is  light,  being  made  of  pressed  steel,  and  in  the  end  pays  for 
the  added  cost.  This  type,  as  well  as  some  types  without  roller 
bearings,  has  an  advantage  in  having  bearings  of  different  sizes 
interchangeable  in  the  same  hanger. 

The  rigid  types  are  more  difficult  to  adjust  and  require  the 
wedging  or  moving  of  the  whole  hanger  in  order  to  change  the 
alignment.  The  drop  hangers  are  intended  for  over-head  use  but 
can  be  used  on  the  floor.  The  size  of  a  hanger  depends  upon  the 
duty  to  be  imposed  upon  it  and  the  size  of  the  pulleys  to  be  used 
on  the  shaft.  Hangers  vary  in  size  according  to  the  distance  from 
the  wall,  or  other  support,  to  the  center  of  the  shaft  opening. 

Wall  hangers  art  for  use  on  side  walls  although  they  can  be 
used  on  posts.  Their  design  is  such  that  they  are  more  rigid  for 
side  wall  use  than  are  drop  hangers.  A  post  hanger  has  much  less 
distance  from  its  base  to  the  center  of  the  shaft  opening  than  a 
wall  hanger  because  it  is  designed  for  use  on  posts  where,  ordinarily, 
no  allowance  need  be  made  for  pulley  clearance.  The  matter  of 


16  SCHOOL  SHOP  INSTALLATION 

adjustment,  as  explained  in  connection  with  drop  hangers,  also 
applies  to  wall  and  post  hangers. 

Hangers  should  be  of  sufficient  size  to  allow  of  plenty  of  free- 
dom for  pulleys  and  belts,  and  the  possibility  of  adding  larger 
pulleys  in  the  future  should  be  considered.  The  distance  apart 
that  hangers  should  be  placed  depends  upon  the  size  of  the  shaft- 
ing, the  number  and  sizes  of  pulleys  the  latter  will  carry,  the  amount 
of  power  to  be  delivered  or  taken  at  certain  points  in  the  shaft, 
and  the  direction  and  pull  of  the  belting.  In  the  best  practice 
and  in  order  to  obtain  stiffness,  hangers  are  placed  each  side  of  the 
receiving  pulley,  the  pulley  connecting  with  the  secondary  shafting 
and  any  pulleys  upon  which  there  are  extra  demands,  like  those  to 
which  a  large  planer  is  connected.  Where  convenient,  belting 
should  be  distributed  alternately  to  one  side  and  then  to  the  oppo- 
site side  of  a  shaft  in  order  to  balance  the  pulling  forces  as  much  as 
possible  and  save  wear  on  the  bearings.  It  is  evident  that  if  suc- 
cessive belts  run  to  one  side  of  the  shafting  with  none  running  to 
the  opposite  side  there  will  be  excessive  wear  upon  the  bearings. 
The  same  principle  would  hold  in  regard  to  belting  from  above  and 
below  the  shaft. 

The  following  table  and  formulas  can  be  used  as  a  guide  in 
determining  the  distance  apart  of  hangers.  This  table  is  good  for 
normal  conditions  only  as  regards  number,  size,  and  weight  of 
pulleys,  pull  of  belts,  work  to  be  done,  etc.  Where  the  work  to  be 
done  is  excessive  the  hangers  should  be  closer  together  than  is 
indicated  in  the  table. 

Kimball  and  Barr  say  that  the  allowable  distance  between 
hangers  can  be  determined  by  the  formula  L  =  7V  d2  for  shafting 
without  pulleys,  and  L  =  5^d2  for  a  shaft  carrying  the  usual 
amount  of  pulleys.  L  =  the  distance  in  feet,  d  =  the  diameter  of  the 
shaft  in  inches.  As  an  example,  find  the  distance  apart  of  bearings 
for  a  2"  shaft  carrying  the  usual  amount  of  pulleys.  Substitut- 
ing 2  for  d  in  the  second  formula,  we  get  L  =  5^2X2  =  7.93  ft. 
or  practically  8  ft.  apart.  The  larger  the  shaft  the  farther  apart 
may  the  bearings  be. 


POWER  TRANSMISSION  17 

TABLE  OF  DISTANCES  OF  HANGERS  APART 

CENTER  TO  CENTER — NORMAL  CONDITIONS 


Diameter 
of  Shaft 
Inches 
1  

Distan 
tween  K 
Feet 
5 

ce  be- 
fangers 
Inches 
0 
9 
6 
3 
0 
6 
3 
9 
3 
0 

5 

\v 

6 

\y 

7 

2  

8 

8 

iy 

9 

2V 

9 

3  :  

10 

11 

11 


9.  First  Alignment;  Hangers  and  Shafting. — The  first  align- 
ment of  shafting,  preparatory  to  locating  the  hangers,  may  be 
obtained  in  several  ways.  In  the  first  way,  having  marked  for  the 
two  extremities  of  the  proposed  line,  the  transit  is  placed  directly 
under  the  point  where  one  extremity  is  to  be.  A  plumb  line  can 
be  used  for  this  determination.  The  transit  is  then  accurately 
leveled  and  sighted  at  the  point  at  the  other  extremity.  Then,  if 
the  movement  of  the  transit  in  the  horizontal  plane  is  prevented 
by  adjustments,  as  many  intervening  points  may  be  sighted  and 
marked  as  is  wished.  A  very  similar  procedure  is  followed  when 
aligning  for  hangers  on  the  side  wall,  only  in  this  case  the  vertical 
movement  of  the  transit  is  prevented  so  that  it  will  always  sight 
in  a  level  plane.  Targets  are  used  in  connection  with  the  transit 
in  this  method  of  aligning. 

In  using  a  stretched  line  method,  two  points,  near  the  extrem- 
ities of  the  position  that  the  shaft  is  to  take,  must  be  known.  A 
line  is  stretched  tight  exactly  thru  these  points,  and  by  it  can  be 
determined  any  intervening  points.  A  cord  is  not  desirable  as  it 
can  not  be  stretched  as  taut  as  it  should  be.  A  piano  wire  is  very 
good  for  this  purpose. 


18  SCHOOL  SHOP  INSTALLATION 

In  a  new  shop,  alignment  may  be  effected  by  nailing  blocks  on 
the  floor  directly  under  where  the  shaft  is  to  be.  By  using  a  straight 
edge  and  level,  and  planing  the  blocks  when  desired,  they  can  be 
made  exactly  level.  A  chalk  line  should  then  be  stretched  across 
the  blocks  and  a  mark  on  them  made.  Over  these  marks  and  by 
means  of  a  plumb  line,  a  center  point  for  each  hanger  can  be  ob- 
tained. By  using  a  template  having  a  center  hole  and  bolt  holes 
for  the  hanger,  and  putting  this  center  hole  on  the  point  located 
by  the  plumb  line,  the  points  for  the  hanger  bolt  holes  can  be 
located.  The  shafting  can  be  located  as  to  distance  above  these 
leveling  blocks  by  using  a  stick  cut  to  a  length  equal  to  the  distance 
from  the  blocks  to  the  position  that  the  bottom  of  the  shafting 
should  have. 

By  using  a  stick  of  the  desired  length,  counter-shafts  on  the 
ceiling  may  also  be  located  parallel  to  the  line  shaft  and  at  a  certain 
distance  from  it.  Counter-shafts  on  the  floor  may  be  located  by 
dropping  a  plumb  line  at  two  points  from  the  main  shaft,  chalking 
a  line  thru  these  points  and  making  the  counter-shaft  parallel  to 
this  line. 

10.  Fastening  Hangers. — Where  it  is  known  that  a  building, 
which  is  to  be  built  of  concrete,  must  support  shafting  hangers,  pro- 
vision should  be  made  in  the  plans  for  the  fastening  of  the  hangers. 
A  more  satisfactory  job  of  installation  can  be  performed  if  materials 
are  imbedded  in  the  green  concrete  when  the  building  is  being 
constructed.     Where  it  is  necessary  to  put  up  shafting  on  old 
concrete,  the  hangers  must  be  bolted  to  the  concrete.    Expansion 
bolts  are  useful  for  this  purpose.    Shaft  hangers  on  wooden  build- 
ings may  be  fastened  by  lag  screws  or  bolts. 

11.  Second  Alignment. — The  second  alignment  of  shafting  in 
the  vertical  plane  can  be  performed  by  tightly  stretching  piano 
wire  horizontally  opposite  the  center  of  the  extremities  of  the  shaft 
and  equidistant  from  the  shaft  at  each  end.    The  bearings  can  then 
be  so  adjusted  that,  by  measurement,  it  is  found  that  the  shaft  is 
exactly  parallel  to  the  wire  thruout  its  length. 

To  align  the  shaft  in  the  horizontal  plane  or  make  it  level, 


POWER  TRANSMISSION 


19 


hangers  or  hooks,  similar  to  those  shown  in  C,  Fig.  1  are  hung  over 
the  shaft  A  to  support  on  their  lower  ends  a  straight  edge  B.  Nuts 
E  on  the  hanger  raise  or  lower  the  straight  edge  to  make  it  parallel 
to  the  shaft.  The  gauge  F  will  aid  in  making  the  distance  between 
each  end  of  the  straight  edge  and  the  shaft  equal.  The  straight  edge 
should  be  made  of  pine  and  should  be  at  least  I"  thick.  The  upper 
edge  should  be  planed  perfectly  straight.  The  level  D  is  put  on 
this  edge  and  from  it  one  can  tell  when  the  boxes  have  been  so 


Fig.  1 

adjusted  that  the  shaft  is  level.    This  is  an  efficient  and  simple 
method. 

12.  Set  Collars. — Every  shaft  should  have  two  set  collars  to 
limit  the  end  play.  They  should  never  be  placed,  however,  so  as 
to  allow  of  no  end  play,  for  any  shaft  will  run  better  and  the  bear- 
ings wear  longer  if  a  small  amount  of  end  play  is  allowed.  The 
collars  are  sometimes  placed,  one  at  each  end  of  the  shaft.  This 
plan  is  not  so  good  as  that  of  putting  them  one  at  each  side  of  a 
centrally  located  bearing,  as,  in  the  first  case,  variations  in  temper- 
ature, especially  in  a  long  shaft,  will  change  the  amount  of  end 
play  and  either  permit  of  too  much  play  or  so  little  play  as  to  cause 
undue  friction.  The  second  method  will  cause  neither  of  these 
troubles. 


20 


SCHOOL  SHOP  INSTALLATION 


13.  Aligning  Pulleys. — In  order  to  have  belts  run  true  on  pulleys 
of  parallel  shafting,  it  is  necessary  to  have  the  two  shafts  in  line 
vertically  and  horizontally.  They  can  be  placed  in  parallel  hori- 
zontal planes  by  getting  each  one  level.  If  they  are  not  to  be  very 
far  apart,  they  can  be  located  in  parallel  vertical  planes  by  using 
a  stick,  cut  to  the  desired  length,  as  a  means  for  making  them 
equidistant  from  one  another  at  all  points. 

A  Where  shafts  are  a  considerable  distance 

apart  their  alignment  in  parallel  vertical 
planes  may  be  tested  by  dropping  plumb 
lines  to  the  floor,  from  which  points  on  the 
floor  may  be  located  and  a  chalk  mark 
struck.  These  marks  will  be  directly  under 
the  shaft  and  by  careful  measurement  with 
a  steel  tape  one  can  determine  whether  they 
are  the  same  distance  apart  at  all  points 
or  not.  If  they  are  not  far  out  of  line  they 
can  be  adjusted  by  means  of  the  bolts  in  the 
hanger. 

Not  only  must  the  shafts  be  aligned  properly  but  it  is  also 
necessary  that  the  centres  of  the  pulleys  be  in  line.  Referring  to 
Fig.  2  and  assuming  that  the  shafts  are  in  line,  the  pulley  F  is 
fixed,  and  it  is  desired  to  bring  pulley  E  in  line  with  pulley  F,  a 
string  A-B  is  drawn  taut  across  the  pulleys  close  to  the  shaft  and 
at  a  distance  of  J^"  or  so  from  pulley  F.  The  pulley  E  is  then 
moved  until  the  distances  a,  b,  c,  d,  between  the  rims  and  the 
string  are  all  equal.  In  case  one  pulley  is  wider  than  the  other, 
due  allowance  should  be  made  so  that  the  centres  of  the  pulleys 
are  fixed  in  line. 

14.  Pulleys.  —  The  pulleys  commonly  used  are  of  the  fol- 
lowing kinds:  cast-iron  solid,  cast-iron  split,  wood  split,  pressed 
steel,  and  paper.  Those  types  which  are  held  in  place  on  the 
shafts  by  means  of  keys  or  set-screws  are  not  as  desirable  as 
those  that  can  be  clampsd  tight.  A  key  weakens  a  shaft  and 
when  it  is  necessary  to  change  a  pulley,  it  is  often  also  necessary 


POWER  TRANSMISSION  21 

to  cut  a  new  key-way.  Pulleys  with  set  screws  do  not  hold  as 
well  as  is  often  wished.  Key- ways  in  cold-rolled  steel  shafting 
often  release  the  tension  in  the  surface  of  the  shaft,  putting  it  out 
of  form. 

The  cast-iron  solid  pulley  is  the  poorest  type  because  it  is  not 
easily  taken  off  or  put  on,  is  not  adjustable  to  various  sizes  of 
shafting,  is  easily  broken  and  requires  a  key  or  set-screw  to  hold  it. 

Cast-iron  split  pulleys  are  better,  for  they  are  more  easily  taken 
off  or  put  on  and  have  bushings  which  make  them  adjustable  to 
shafts  of  different  sizes.  They  are  easily  broken,  however. 

Wood  split  pulleys  are  fairly  good,  but  they  loosen  rather 
easily,  squeak,  and  are  affected  by  atmospheric  conditions.  They 
have  bushings  of  various  sizes  and  make  good  belt  contact. 

Paper  pulleys  are  light,  cheap,  non-breakable  and  give  good 
belt  contact,  but  they  require  keys  and  are  not  adjustable  to 
shafts  of  varying  sizes. 

Pressed  steel  pulleys  are  the  best  and  latest  development.  They 
are  light,  durable,  fasten  tightly,  are  easily  changed,  do  not  break 
and  have  interchangeable  bushings. 

Pulleys  on  which  a  belt  is  not  shifted  should  have  a  crown. 
This  crown  aids  materially  in  keeping  the  belt  in  the  center  of  the 
pulley.  If  it  were  not  for  this  crown,  arms  would  be  necessary  to 
keep  the  belt  in  place  and  they  wear  the  edge  of  the  belt.  Tight 
and  loose  pulleys,  upon  which  a  belt  is  shifted,  do  not  ordinarily 
have  crowns. 

15.  Placing  Pulleys. — Pulleys  should  be  placed  as  near  bear- 
ings as  possible  to  prevent  undue  deflection  of  the  shafting  and 
corresponding  friction.     Tightening  or  guide  pulleys,  when  used, 
should  be  on  the  slack  side  of  belt  near  the  smaller  pulley.    Pulleys 
should  be  a  trifle  wider  than  the  belts  to  be  used  on  them  to  prevent 
over-hang  of  the  belt. 

16.  Shaft  Couplings. — There  are  several  good  styles  of  shaft 
couplings.     Those  which  require  no  keys  and  which  have  no  bolt 
heads  or  other  projections  to  catch  things  and  cause  damage  are 
preferable. 


22  SCHOOL  SHOP  INSTALLATION 

17.  Rules  for  Finding  Sizes  and  Speeds  of  Pulleys. — Of  the 
two  pulleys,  the  driving  pulley  is  the  one  nearest  the  source  of 
power. 

1.  To  Find  the  Size  of  Driving  Pulley  multiply  the  diameter  of 
the  driven  pulley  by  the  revolutions  it  should  make  and  divide 
the  product  by  the  revolutions  of  the  driver. 

Example:  The  dia.  of  the  driven  pulley  is  12"  and  it  should 
make  240  R.  P.  M.  The  R.  P.  M.  of  the  driving  pulley  is  160. 
What  should  its  diameter  be? 

Answer:  12  x  240  =  2,880  and  2,880  divided  by  160  =  18",  dia. 
of  the  driving  pulley. 

2.  To  Find  the  Size  of  Driven  Pulley  multiply  the  dia.  of  the 
driver  by  its  R.  P.  M.  and  divide  the  product  by  the  R.  P.  M.  of 
the  driven. 

Example:  A  driving  pulley  18"  in  dia.  makes  160  R.  P.  M.  and 
the  driven  pulley  should  make  240  R.  P.  M.  What  should  be  its 
diameter? 

Answer:  18  X  160=  2,880,  and  2,880  divided  by  240=  12", 
dia.  of  the  driven  pulley. 

3.  To  Find  the  Number  of  Revolutions  (R.  P.  M.)  of  Driven  Pulley 
multiply  the  dia.  of  the  driver  by  its  R.  P.  M.  and  divide  the 
product  by  the  dia.  of  the  driven. 

Example:  A  driver  18"  in  dia.  makes  160  R.  P.  M.,  and  the 
dia.  of  the  driven  pulley  is  12".  What  is  the  R.  P.  M.  of  the 
driven? 

Answer:  18  X  160  =  2,880  and  2,880  divided  by  12  =  240,  the 
R.  P.  M.  of  the  driven. 

4.  To  Find  the  R.  P.  M.  of  the  Driving  Pulley  multiply  the 
R.  P.  M.  of  the  driven  pulley  by  the  dia.  of  the  driven  pulley  and 
divide  this  product  by  the  dia.  of  the  driving  pulley. 

Example:  The  R.  P.  M.  of  the  driven  are  500  and  its  dia.  is 
6"  while  the  dia.  of  the  driving  pulley  is  15".  What  is  the  R.  P.  M. 
of  the  driving  pulley? 

Answer:  500  X  6  =  3,000,  and  3,000  divided  by  15  =  200,  the 
R.  P.  M.  of  the  driving  pulley. 


POWER  TRANSMISSION  23 

BIBLIOGRAPHY 


1.  KENT,  Mechanical  Engineer's  Pocket  Book. 

2.  KIMBALL  AND  BARR,  Machine  Design. 

3.  HALSEY,  Handbook  for  Machine  Designers. 

4.  SWINGLE,  Handbook  for  Millwrights. 


CHAPTER  II 

MOTORS  AND  CURRENTS 

18.  General    Considerations. — In  a  book  of  this  nature  it 
would  not  be  possible  to  give  complete  information  for  the  choice 
of  the  type,  style  or  size  of  electric  motors.    This  is  a  matter  about 
which  teachers  should  get  advice  from  an  engineer  or  the  service 
department  of  motor  manufacturers.     However,   a  discussion  of 
the  problem  is  of  advantage  to  the  teacher  if,  by  such,  he  sees  the 
many  technical  points  involved  in  properly  choosing  a  motor,  and 
realizes  the  advisability  of  consulting  an  authority  in  the  solution 
of  the  problem  as  a  whole. 

The  conditions  cf  capacity  and  efficiency  are  both  of  import- 
ance in  any  .motor  installation.  The  installation  of  a  motor  having 
too  large  a  capacity  should  be  avoided  unless  an  increase  in  the 
load  is  to  be  expected  in  the  near  future,  such  as  additions  of  equip- 
ment, for  the  efficiency  of  a  motor  is  generally  at  its  maximum  at 
its  normal  rated  output.  Too  small  a  motor  is  also  undesirable  as 
it  is  unquestionably  liable  to  be  subjected  to  over-loads,  causing 
the  motor  to  burn  out,  making  temporary  use  of  the  machinery 
impossible. 

19.  Two  Types  of  Work. — The  school  shop  ordinarily  offers 
two  varieties  of  work  for  the  motor,  i.  e., 

a)  work  which  requires   the  motor  to  operate  automatically 
at  a  practically  constant  speed,  regardless  of  load  changes  or  other 
conditions. 

b)  work  in  which  the  power  varies  regardless  of  the  speed,  or 
where  speed  variations  with  constant  torque  may  be  desired. 

In  (a)  an  example  is  found  in  the  case  of  line-shaft  equipments 
with  a  number  of  machines  operated  by  the  same  motor,  and  where 
only  slight  variations  are  desired.  In  this  case  the  D.  C.  shunt 
of  slightly  compounded  motor  or  the  A.  C.  induction  motor  would 

24 


MOTORS  AND  CURRENTS  25 

answer  the  purpose  and  the  choice  would  depend  upon  the  type  of 
current  available. 

Work,  of  the  nature  explained  in  (b)  is  found  in  certain  types 
of  individual  drive  machinery,  such  as  machine  or  wood  lathes 
where  the  maximum  allowable  turning  speed  varies  inversely  as 
the  diameter  of  the  cut.  Such  work  is  best  satisfied  by  the  use  of 
D.  C.  shunt  or  slightly  compounded  motors,  as  their  speed  is 
readily  controlled. 

20.  Advantages  of  A.  C.  Motors.— 

1.  Motor  runs  with  little   change  of  speed  under  a 

heavy  load. 

2.  The  usual  current  in  cities  is  A.  C. 

21.  Advantages  of  D.  C.  Motors. — 

1.  Wider  air  gap,  allowing  more  wear  in  the  bearings 

before  the  motor  needs  repair. 

2.  The  possibility  of  variations  of  speeds.     This  is  a 

decided  advantage. 

22.  Data  Required  in  Determining  the  Choice  of  Motor. — The 
following  points  are  essential  for  the  proper  choice  of  type  and  size 
of  motor: 

1.  Individual  or  group  drive? 

2.  If  individual  drive,   the  machine  and  the  kind  of 

work  to  be  done  on  it. 

3.  If  the  group  drive,  and  some  of  the  machines  operate 

intermittently,  give  details  of  the  work  of  these 
machines. 

4.  Statement  of  insurance  rules. 

5.  Is  variation  of  speed  desirable? 

6.  How  is  this  variation  controlled? 

7.  Speed  of  machine,  size  of  pulley  and  belt? 

8.  Is  belt  pull  at  top  or  bottom? 

9.  Will  there  be  any  combustible  material  near  motor? 

(shavings,  saw-dust,  etc.) 

10.  Where  will  motor  be  fastened? 

11.  Voltage  and  type  of  current. 


26  SCHOOL  SHOP  INSTALLATION 

This  list  does  not  include  all  that  might  be  necessary  but  gives 
one  an  idea  of  the  advisability  of  seeking  competent  advice  when 
choosing  a  motor. 

23.  Planning  for  Motor  Drive. — In   arranging  motor-driven 
school  shop  equipment  the  following  points  should  be  observed: 

1.  To  provide  ample  aisles  and  operating  and  stock 

space  between  machines. 

2.  To  arrange  the  machines   so  that  the  routing  of 

work,  in  some  order,  can  be  effected. 

3.  To  locate  the  machines  so  that  good  lighting  con- 

ditions exist. 

4.  To  locate  motors  where  they  are  accessible. 

5.  To  guard  motors,  shafting  and  belts  properly  and 

yet  make  them  accessible  for  cleaning,  oiling,  re- 
pairing and  adjusting. 

24.  Installation    of    Electric    Motors. — -Ths    foundation    for 
electric  motors  must  be  solid,  to  prevent  vibration.    Solid  masonry 
or  concrete  is  the  best  material,  but  wood  or  timber  framing  can 
be  used.    All  motors  should  be  insulated  from  contact  with  metal. 
Great  care  should  be  taken  in  aligning  the  motor  shaft  with  the 
driven   shaft   if   the   latter  is   to   be   connected   directly   to  the 
motor. 

25.  Care  of  Motors. — Only  the  best  quality  of  oil  and  grease 
should  be  used  on  the  bearings.     The  best  quality  of  lubricant  is 
more  economical  than  worn  bearings.     Bearings  provided  with 
oiling  rings  should  have  a  good  grade  of  dynamo  oil,  and  should  be 
filled  to  the  top  of  the  over-flow  plugs.    The  plugs  should  be  kept 
free,  and  all  dirt,  dust  and  gritty  materials  must  be  kept  out  of  the 
bearings.    Excessive  belt  tension,  which  heats  the  bearings,  should 
be  avoided.     The  commutator  and  brushes  should  be  kept  clean. 
Emery  cloth  is  injurious  to  the  commutator  and  brushes.    A  clean 
cloth  or  waste  should  be  sufficient  to  remove  the  dirt. 

Sparking  at  the  commutator  of  D.  C.  mo  tors  is  often  caused  by: 
1.     An  over-load.     Release  some  of  the  load. 


MOTORS  AND  CURRENTS  27 

2.  Improper  brush  adjustment.       If  a  brush  fits  the 

commutator  properly,  the  entire  face  of  it  will  be 
glazed. 

3.  Improper  brush  contact — 

(a)  Grease  or  dirt  accumulations. 

(b)  Brushes  may  stick  in  the  holder  and  need  sand- 

papering to  free  them. 

(c)  Increased   brush    pressure   may    be   needed — 

change  adjustment  on  spring. 

BIBLIOGRAPHY 

1.  Industrial   Application    of    Motors — American    Handbook 
for  Electrical  Engineers. 

2.  Installation,   Care   and   Repair   of   Electrical   Motors   in 
Industrial  Operations,  Electrical  Review,   1909,  Vol.  55,  pp.  795, 
845,  892,  944. 

3.  Selection    of    Direct-Current    Motors    for    Factory    Use, 
Engineering  Magazine,  1911. 

4.  Selection  of  Motors  for  Different  Kinds  of  Service — F.  B. 
Crocker  and  M.  Arendt,  Electrical  World,  Nov.  1907. 

5.  Choice  of  Motors  for  Machine  Tools,  Kent's  Mechanical 
Engineer's  Pocket  Book. 

6.  Relative  Costs  of  Group  and  Individual  Drive — G.   E. 
Sanford,  General  Electric  Review,  Vol.  15,  p.  17. 

7.  Catalogs  and  literature  distributed  by  motor  manufacturers. 


V 

CHAPTER  III 

INSTALLATION  OF  METALWORKING  EQUIPMENT 

26.  General  Considerations. — In  general,  the  installation  of 
metalworking  equipment  requires  a  knowledge  of  the  floor  space 
necessary  for  each  machine  or  object  of  equipment,  the  space  for 
the  operator  to  work  in  and  the  space  for  the  machines  to  operate 
in.    Also,  the  placing  of  the  machines,  as  regards  the  light  for  their 
operation,  should  be  considered.     Sufficient  aisles  should  be  pro- 
vided, and  the  machines  located  so  as  to  be  accessible  for  adjust- 
ment or  repair.    Safety  points  on  machines,  shafting,  belts,  motors, 
etc.  should  receive  careful  attention.      Storage  places  for  tools, 
raw  and  finished  stock  are  necessary.    The  placement  of  machines, 
in  respect  to  their  convenience  to  each  other,  should  be  considered. 
Drills,  for  instance,  are  used  in  connection  with  several  machines 
and  operations  and  should  be  centrally  located  in  respect  to  these 
machines,  if  possible. 

It  is  possible,  sometimes,  to  economize  on  space  by  doubling 
up  on  equipment,  i.  e.,  a  bench,  used  for  chipping  and  filing,  may 
also  be  used  for  sheet-metal  work,  or  in  connection  with  auto  re- 
pair, depending  upon  the  arrangement  of  the  room  and  the  schedule 
of  classes. 

Small  machines  should  be  bolted  to  the  floor  or  foundation. 
Heavy  machines  should  be  grouted  or  wedged  with  shingles  and 
bolted.  On  concrete  floors,  expansion  bolts  may  be  used  to  ad- 
vantage. 

Speeds  and  sizes  of  the  pulleys  will  be  determined  from  the 
specifications  furnished  by  the  manufacturers. 

27.  Planer. — Daylight  should  come  from  the  left  of  the  oper- 
ator as  he  is  at  work,  if  possible.    This  would  mean  that  the  work- 
ing stroke  of  the  planer  would  be  away  from  the  light.     If  thb 
arrangement  is  not  convenient,  then  the  planer  should  be  placed 

28 


METALWORKING  EQUIPMENT  29 

so  that  the  working  stroke  is  parallel  to  the  windows  and  the  oper- 
ator faces  the  light.  Artificial  light  should  be  about  2  ft.  in  front 
of  the  tool-post  and  over  the  center  of  the  platen. 

There  should  be  4  ft.  of  space  between  the  end  of  the  table  or 
platen  and  the  wall,  or  other  objects,  after  the  extreme  travel  of 
the  platen.  Otherwise,  the  table,  in  running  off  the  gear,  as  it 
does  sometimes,  might  pinch  a  person  against  the  wall  and  injure 
him  most  seriously.  There  should  be  at  least  a  4  ft.  space  parallel 
to  the  side  of  the  planer  for  the  operator. 


Level 


Fig.  3 

A  consideration,  often  overlooked,  is  the  necessity  of  leveling 
the  bed  of  the  planer  or  the  ways  in  order  to  obtain  the  best  quality 
of  work  from  the  machine.  It  should  be  leveled  across  the  ways 
and  lengthwise  of  them.  To  get  the  two  ways  level,  put  two  round 
bars,  of  the  same  diameter,  in  the  ways  as  shown  in  Fig.  3,  and 
across  the  bars  place  a  level.  Bolster  up  the  planer  until  it  is  level 
at  this  end  and  wedge  or  grout  it.  Level  it  thus  at  each  end  and 
intervening  points. 

To  test  the  ways  to  see  if  they  are  concaved  or  convexed 
lengthwise  of  the  planer,  place  the  bars  in  the  ways  as  before, 
but  in  place  of  the  level  put  a  straight  edge  across  the  bars.  In 
this  case,  the  bars  should  be  rather  short.  Similarly,  at  a  distance 
of  2  to  4  ft.  along  the  bed  place  two  more  bars  and  a  straight  edge. 
Across  the  two  straight  edges,  and  connecting  them,  lay  a  level, 
Fig.  4.  Repeat  this  whole  procedure  by  moving  these  tools  along 


30  SCHOOL  SHOP  INSTALLATION 

the  bed  but  have  each  space  being  leveled  overlap  the  previous 
space  leveled.  By  this  means  the  ways  can  be  leveled  lengthwise 
and,  by  wedging,  or  grouting  and  fastening  to  the  floor,  the  planer 
can  be  held  level. 

28.  Lathe. — It  is  preferable  that  daylight  should  come  from 
the  right  as  the  operator  is  at  work  at  the  lathe,  so  that  he  casts  no 
shadow  on  the  work.  Artificial  light  should  be  directly  over  the 
bed  of  the  lathe  near  its  center.  Lathes,  placed  end  to  end,  should 
have  at  least  2  ft.  of  space  between  them  to  allow  for  the  opening 
of  cages  over  the  gears  and  for  passageway.  Lathes,  placed  back 

Lcve/^Straighf 


Ways 


Fig.  4 

to  back,  should  have  a  1  ft.  space  between  those  parts  of  the  lathes 
nearest  meeting.  The  lathe  bed  should  be  leveled  as  explained  for 
a  planer,  and  the  legs  properly  supported  by  shingle  wedges  or 
grout.  The  legs  should  be  bolted  to  the  foundation. 

29.  Drill  Press. — Daylight  should  come  from  the  left  or  right 
Artificial  light  should  be  at  the  height  of  the  head  to  the  left  or 
right  of  the  center.     There  should  be  3  ft.  of  working  space  at  th : 
front  and  the  two  sides.     The  machine  should  be  set  so  that  the 
table  is  level  as  it  is  often  necessary  to  set  up  work  by  the  use  of 
the  level. 

30.  Milling  Machine. — There  should  be  space  on  three  sides 
for  the  operator.  Light  should  come  from  the  left  or  right  if  possible. 
Artificial  light  should  be  in  the  front  of  the  center  of  the  machine 
just  above  the  head. 


METALWORKING  EQUIPMENT 


31 


31.  Shaper. — Light  should    come  from  the  left  or  right  as 
operator  works.     Three  feet  of  space  beyond  the  extreme  travel 
of  the  slide  is  desirable. 

32.  Forge. — Double  forges  have  an  advantage    in  that  the 
initial  cost  and  that  of  operation  is  less,  and  also  because  there  is 
an  economy  of  space  with  this  type.     Further  economy  of  space 
is  often  gained  by  placing  them  at  an  angle  of  45  degrees  with  the 
imaginary  line  thru  the  center  of  the  forges. 

Single  forges  should  be  placed  about  5  ft.  4"  apart  on  centers  as 
a  minimum. 


«— 26  — H 


f  \  V\ 

FORGE        \  \X      i 


=/' 


Fig.  5 


The  hood  should  be  at  the  left  and  also  the  lever  that  controls 
the  air. 

33.  Anvil. — There  should  be  from  24"  to  26"  of  space  between 
the  anvil  and  the  forge.     The  anvil  should  be  turned  at  an  angle 
of  about  50  degrees  and  the  center  of  the  anvil  should  be  about 
two  inches  to  the  front  of  the  center  of  the  forge,  Fig.  5. 

There  should  be  sheet-iron  around  the  anvil  if  it  is  on  a  wooden 
floor.  A  wood  mount  for  the  anvil  set  2  ft.  in  the  ground  or  in 
concrete  is  good.  Cement  mounts  or  stands  crumble.  Iron  stands 
are  clumsy,  in  the  way  of  the  feet  of  the  worker  and  have  openings 
around  the  anvil  into  which  tools  are  dropped  and  are  bothersome 
to  extract.  For  a  grown  person,  the  top  of  the  anvil  should  be 
about  28"  above  the  floor. 

34.  Blower. — Individual  blowers  for  each  forge   are   advan- 
tageous for  it  is  then  not  necessary  to  run  a  big  blower  sufficient 
for  all  forges  when  only  a  few  are  being  used.     The  cost  of  installa- 


32  SCHOOL  SHOP  INSTALLATION 

tion  for  underground  blast  piping  is  saved,  the  loss  of  power  due 
to  friction  is  minimized  and  the  total  power  required  is  less,  for, 
with  a  single  large  blower,  the  pressure  is  kept  up  to  a  certain 
maximum  at  all  times. 

In  case  it  seems  advisable  to  install  a  blower  and  exhauster,  a 
motor  driven  fan  is  preferable.  The  motor  can  be  placed  between 
the  fans  of  the  blower  and  exhauster,  having  the  shaft  extend  each 
way  into  the  fans. 

In  planning  a  forge  room,  it  would  be  advisable  to  submit,  to 
the  engineering  department  of  reputable  makers  of  forge  equip- 
ment, the  dimensions  of  the  forge  room,  as  well  as  the  number  of 
the  forges  to  be  installed  and  the  preferred  location  of  same.  The 
engineering  department  will  then  prepare  a  suggestive  lay-out 
showing  an  economical  arrangement  of  forges,  anvils,  and  under- 
ground ducts. 


CHAPTER  IV 

INSTALLATION  OF  WOODWORKING  EQUIPMENT 

35.     General  Considerations. — No  hard  and  fast  rules  can  be 
given  that  will  determine  for  one  the  exact  arrangement  of  machin- 

-H  )'  I — 


/ 

-   — 
1     1 

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i 

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1 

j 

16*              *) 

r 

I 

5URFACER      co 
j 

J 

•                ..         i 
i  

4                                                                                                           17' 

.__ 

— 
| 

r—  • 



• 

r 


/ 

, 

r 

—  i 

-  j 

rl 

1 
1 

I61' 

\ 

10  2 

i 

'ig-  6 

33 

34 


SCHOOL  SHOP  INSTALLATION 


ery.     Existing  conditions  are  varied  and  only  points  for  consider- 
ation can  be  shown. 

One  should  know  the  approximate  floor  space  necessary  for 
different  machines  as  well  as  the  operating  and  stock  spaces  deemed 
essential.  The  floor  spaces  will  be  given  by  the  manufacturer  in 
the  specifications  of  the  machines.  The  operating  and  stock 
spaces  for  various  machines  should  be  approximately  as  shown  in 


LATHE 


AUT  GRINDER 

-J. 


0 


""V 


MORJri5CR|   _S_ 


14      o 

!_j__i 1 

h 6' 


\ 


Fig.  7 


N 
\ 
\ 

jAUT.  GRINDLR 

1    '                         ! 
i  / 

BAND  SAW 


Fig.  8 


WOODWORKING  EQUIPMENT 


35 


Figs.  6  and  7.  These  are  respectively  designated  by  O  and  S.  It 
might  happen  that  an  S  space,  allowed  for  one  machine,  might 
overlap  an  -5*  space  for  another  machine  with  no  inconvenience. 
For  instance,  an  arrangement  like  that  shown  in  Fig.  8,  where  the 
stock  space  for  the  band  saw  overlaps  that  for  the  automatic 
grinder,  would  not  be  a  serious  inconvenience. 

In  locating  the  different  machines, 
it  is  necessary  that  the-  pulleys  on  the 
machines  line  up  with  the  pulleys  on 
the  line  or  counter-shaft  over  which 
the  belts  for  the  machines  under  con- 
sideration run.  If  in  Fig.  9,  a  wire  or 
strong  cord  is  stretched  tight  across 
the  upper  and  lower  rim  of  pulley  C 
on  the  line-shaft  close  to  the  shaft,  and 


FLOOR  LINE- 


\ 


Fig.  9 


Fig.  10 


the  machine  E  is  so  moved  as  to  bring  the  rim  of  the  pulley  D 
just  to  the  line  also,  and  pulleys  C  and  D  are  plumbed  with  a 
plumb  bob,  as  in  Fig.  10,  there  will  be  no  trouble  with  the  belts 
running  off,  provided,  of  course,  that  the  pulleys  are  properly 
hung  on  their  respective  shafts. 

The  speeds  at  which  different  machines  should  run  are  given 
in  the  specifications  by  the  manufacturers.  Formulas  for  figuring 
sizes  and  speeds  of  pulleys,  width  of  belts,  etc.,  are  given  in  the 
chapters  on  "Power  Transmission"  and  "Belting." 


36 


SCHOOL  SHOP  INSTALLATION 


36.  Speeds  of  Various  Machines. —  For  reference,  the  speeds 
of  various  machines  are  given  below : 

1.  Grindstone — circumferential  speed  of  from  600  to  800  ft. 
per  minute. 

2.  Crosscut-saw  and  rip-saw — rim  speed  of   10,000  ft.   per 
minute. 

3.  Jointer— speed  of  cylinder,  4,000  to  5,000  R.  P.  M.  for  large 
size,  and  about  5,000  R.  P.  M.  for  6"  knives. 

4.  Lathe— variations  of  spindle  from  600  to  3,000  R.  P.  M. 

5.  Mortiser — bit  runs  3,450  R.  P.  M.  with  10  to  35  strokes  of 
the  chisel  per  minute.     Driving   pulley   on   countershaft 
makes  1,100  to  1,200  R.  P.  M. 

6.  Surfacer— speed  of  head  4,000  R.  P.  M. 

7.  Band-saw — about  4,500  ft.  per  minute  rim  speed. 

8.  Cut-off  saw — 10,000  ft.  per  minute  rim  speed. 

37.  Emery  Wheel  Speeds.  — 


DIAMETER  OF  WHEEL 
IN  INCHES 

R.  P.  M.  FOR  SURFACE  SPEED 
OF  5,000  FEET  PER  MINUTE 

1  

19,099 
9,549 
6,366 
4,775 
3,820 
3,183 
2,728 
2,387 
1,910 
1,592 
1,364 
1,194 
1,061 
955 

2  

3 

4 

5 

6                        

7          

8     

10  

12 

14 

16                              

18     

20  ... 

WOODWORKING  EQUIPMENT  37 

38.     Circular  Saw  Speeds. — 


SIZE  OF  SAW  IN  INCHES 

R.  P.  M. 

8  •  
10         .  .            

4,500 
3,600 

12  
14 

3,000 
2,585 

16                                            

2,222 

18               .              '''*.-. 

2,000 

20  

1,800 

39.  Horse-Power  Required  for  Woodworking  Machines. — 
This  can  be  stated  only  approximately  due  to  varying  conditions 
of  work  to  which  machines  are  subjected,  such  as  whether  wood  is 
soft  or  hard,  1"  or  3"  thick,  whether  the  machines  are  kept  in  good 
condition  or  not,  etc.     The  general  requirements  are  as  follows: 

1.  Cut-off  saws  require  2  to  4  horse-power. 

2.  Crosscut  and  rip  saws  require  3  to  5  H.  P. 

3.  Surfacers,  18"— 5  to  7  H.  P.;  24"— 7  to  10  H.  P. 

4..    Jointers,  6"—  \l/2  H.  P.;  8"— 2  to  3  H.  P.;  16"— 3  to  4  H.  P. 
and  20"— 4  to  5  H.  P. 

5.  Hollow  chisel  mortisers,  !}/£  H.  P. 

6.  Lathe,  %  H.  P.  each. 

7.  Automatic  Grinder,  2  to  3  H.  P. 

40.  Other  Factors  to  Consider. — Woodworking  machines  do 
not  require  as  careful  leveling  as  do  most  metalworking  machines. 
However,  they  should  be  approximately  level,  and,  in  the  case  of 
the  lighter  machines,  should  be  bolted  to  the  floor. 

The  crosscut-  and  rip-saws  should  have  light  from  the  front,  if 
possible;  mortisers  from  the  left  or  right  and  lathes  from  the  front 
or  right  side  as  the  operator  faces  the  lathe.  The  light  for  the 
surfacer,  jointer,  sander  or  band-saw  is  not  so  particular  a  point 
as  for  the  other  machines,  provided  there  is  good  light  in  the  room 
as  a  whole. 


38  SCHOOL  SHOP  INSTALLATION 

Some  attention  might  well  be  given  to  the  routing  of  stock  when 
planning  for  the  placement  of  machines.  From  the  stock  room  or 
cut-off  saw,  the  majority  of  the  stock  goes  to  the  rip-saw,  jointer 
and  surfacer.  This  would  indicate  that  these  machines  might 
well  be  placed  convenient  to  each  other  and  to  the  stock  room. 


PART  TWO  — MAINTENANCE 


CHAPTER  V 

FITTING  EDGE  TOOLS 

41.  Plane  Irons  are  not  all  fitted  alike.  The  usual  equipment 
consists  of  a  jack-plane  for  making  heavy  first  cuts,  a  smooth-plane 
for  making  finishing  cuts  and  for  use  on  broad  surfaces,  and  a  fore- 
plane  or  a  jointer  for  making  a  true,  straight  edge. 

Because  of  the  depth  of  cut  demanded  of  a  jack-plane  and 
because  of  the  fact  that  a  heavy  shaving,  the  full  width  of  the 
blade  or  iron,  would  cause  trouble  by  choking  in  the  throat,  the 
blade  is  usually  ground  a  trifle  rounded,  similar  to  Fig.  11.  This 


Fig.  11 


Fig.  12 


condition  is  obtained  by  bringing  slightly  more  pressure,  first  on 
one  corner  and  then  the  other,  than  on  the  center  of  the  iron,  when 
grinding  it. 

The  smooth-plane  irons  are  ground  perfectly  straight  across 
and  then  about  two  strokes  are  given  each  corner  to  produce  the 
effect  shown  in  Fig.  12.  If  the  corners  are  left  square,  the  different 
cuts,  on  a  broad  surface,  would  be  shown  by  shoulders  or  steps. 
The  rounded  corners  cause  the  cuts  to  blend  unnoticeably  with 
the  rest  of  the  surface. 

The  jointer  iron,  because  of  its  duty  in  forming  a  true  flat  plane 
surface,  is  ground  straight  across  the  edge  and  the  corners  are  left 
square. 

The  angle  of  the  bevel,  Fig.  13,  should  be  about  20  degrees,  or 

39 


40  SCHOOL  SHOP  MAINTENANCE 

so  that  the  bevel  measures  iV  to  }^'  long  on  each  style  of  plane. 
Too  long  a  bevel  will  cause  chattering  and  weaken  the  edge  so  that 
it  will  more  easily  chip.  Hard  wood  requires  less  bevel  than  soft. 
In  grinding  a  plane-iron,  the  cap-iron,  which  is  the  piece  that 
is  clamped  on  the  cutting  iron  or  blade,  should  be  loosened  and 

I— i    s^  kack  as  far  as   the  screw  will  permit 

I *    and   then  fastened  again.     This  will  serve 

as  a  handle  and  also  make  a  quicker  ad- 
|0     justment  than  if  it  were  taken  off  entirely. 

The  proper  way  of  applying  an  iron  to  an 

emery  wheel  or  grindstone  is  shown  by  Fig.  14.  It  should  be 
firmly  grasped  with  the  right  hand  and  the  fingers  of  the  left 
hand  laid  across  it  near  the  cutting  edge.  It  should  be  laid  on  the 
stone  similar  to  a,  Fig.  14,  and  then  raised  with  the  right  hand 
until  the  desired  angle  of  contact  is  made.  This  is  shown  by 
b,  Fig.  14.  If  the  bevel  already  on  the  tool  is  correct,  this  position 
can  be  determined  easily  by  watching  the  cutting  edge  to  see  when 
it  first  comes  in  contact  with  the  stone.  No  tool  should  be  held 
in  one  place  on  the  stone,  but  should  be  moved  slowly  back  and 
forth  across  the  stone  to  keep  the  wear  even  on  both  the  stone  and 
tool.  The  angle  of  contact  with  the  stone,  however,  should  be 
kept  as  constant  as  is  possible.  Otherwise,  the  effect  shown  in 
Fig.  15  will  result,  making  a  stubby,  poor  cutting  edge.  Because 
of  the  difficulty  in  holding 
the  tool  at  the  same  angle, 
a  clamp  or  jig  is  often  used. 
This  has  a  roller  on  the  end, 
opposite  that  on  which  the 
iron  is  clamped,  that  rests 
on  the  stone.  This  clamp 

permits  of  any  ordinary  angle  of  bevel  and  can  aho  be  used  for 
chisels.  In  grinding  on  an  emery  wheel,  great  care  should  be 
taken  not  to  burn  or  draw  the  temper  of  the  tool.  This  can  be 
told  by  a  blue  color  appearing  at  the  cutting  edge.  A  tool  that 
has  been  burned  will  not  keep  an  edge  as  long  as  it  should.  Grind 


FITTING  EDGE  TOOLS 


41 


the  irons  until  a  feather  edge  is  turned  over  on  the  back  of  the 
tool  and  then  stop.  Further  grinding  makes  them  no  sharper  and 
only  wears  away  the  tool. 

Having  ground  the  irons,  the  next  process  is  that  of  whetting. 
This  is  done  on  an  oilstone,  usually  of  a  size  about  6"  x  2"  x  1". 
The  tool  is  grasped  by  the  right  hand  and  the  fingers  of  the  left 
are  laid  across  it  near  the  cutting  edge.     It  is 
I  ^^    applied  to  the  stone  like  a,  Fig.  16,  and  then  is 

Fig.  15  tipped  up  to  the  position  of  b.    It  will  be  noted 

that  this  position  is  not  one  where  the  bevel  is 
flat  on  the  stone,  but  where  it  is  raised  from  the  stone  slightly  at 
the  heel.  Were  the  bevel  laid  flat  on  the  stone,  the  time  required 
to  get  a  fine  cutting  edge  would  be  much  greater  than  by  the  former 
method,  and  the  efficiency  of  the  cutting  edge  would  not  be  in- 
creased. Care  should  be  taken,  however,  to  make  this  angle  only 
slight  and  to  keep  it  constant.  If  a  tool  is  held  properly  in  grinding 
the  form  of  the  bevel  will  be  a  concave  plane  of  the  same  curvature 
as  the  wheel  upon  which  it  is  being  ground.  When  applied  to  the 
flat  surface  of  an  oilstone,  the  tool  will  touch  only  at  the  toe  and 
heel,  and  the  time  necessary  to  whet  it  will  be  short,  even  with  the 
bevel  flat  on  the  stone.  It  is  hard,  however,  especially  for  an 
unskilled  workman,  to  get  a  concave  bevel  on  a  tool,  and  for  that 
reason  it  is  advisable  to 
raise  the  tool  as  ex- 
plained above. 

For  the  beginner  at 
least,  the  motion  of  the 
iron  on  the  oilstone 
should  be  circular  as  in 
Fig.  17.  This  presents 
the  cutting  edge  more  evenly  to  the  stone  and  keeps  the  stone  in  bet- 
ter form.  One  should  keep  changing  the  whetting  area  on  the  stone 
from  time  to  time,  also,  so  that  it  doas  not  become  hollow  in  any  one 
place.  Some  of  the  best  mechanics  give  a  longitudinal  stroke  the  full 
length  of  the  stone  in  whetting,  but  it  is  hard  for  the  beginner  to  do 


Fig.  16 


42  SCHOOL  SHOP  MAINTENANCE 

this  and  keep  the  bevel  correct.  Whetting  should  continue  until  a 
slight  feather  or  wire  edge  can  be  felt  turned  over  on  the  back 
of  the  iron,  extending  clear  across  the  cutting  edge.  To  remove 
this,  lay  the  tool  flat  down  on  the  oilstone  with  the  bevel  up  and 
give  a  few  light  strokes  in  a  circular  motion.  If  the  feather  edge 

is  not  removed  entirely  by  this, 
hold  the  tool  upright  and  draw  it 
crosswise  of  a  piece  of  wood, 
making  a  cut  like  that  of  a 
knife.  One  such  cut  should  re- 
move the  ragged  edge.  In  re- 
placing the  cap-iron,  it  should 
be  clamped  about  %"  fr°m  the 
cutting  edge  for  ordinary  work, 
and  closer  for  cross-grained  hard  wood. 

42.  Chisels  are  ground  and  whetted  exactly  as  are  plane  irons, 
with  the  exception  of  the  angle  of  the  bevel  which  should  be  from 
20°  to  25°  for  paring  chisels  and  about  30°  for  mortising  or  for 
heavy  work  on  hard  wood. 

43.  Turning  Tools. — The  roughing  gouge  should  be  so  ground 
that,  on  looking  down  the  cutting  edge,  as  it  is  held  on  the  rest 
for  cylindrical  cutting,  it  will  have  the  appearance  of  a  semi-circle. 
To  obtain  this  the  angle  a,  Fig.  18,  should  be  about  30°.     It  is  held 
on   the   grindstone   and   oilstone  as  ex- 
plained for  plane-irons,  except  that  it  is 

rolled  with  the  right  hand  from  left  to 
right  to  give  the  cylindrical  bevel. 

The   small  gouge  is  ground   like  the       *  ~~\^ 

roughing  gouge,  but  has  the  corners  of  the 
cutting  edge  ground  farther  back  as  in  B, 

Fig.  18,  to  give  a  better  cutting  edge  on  the  side  where  it  is  so  much 
used.  After  a  gouge  has  been  ground  and  whetted  on  the  bevel,  it  is 
necessary  to  remove  the  wire  edge.  As  this  cannot  be  done  by 
laying  it  flat  on  an  oilstone,  a  slip-stone  is  employed.  The  curve 
of  the  stone  nearest  matching  that  of  the  concave  surface  of  the 


FITTING  EDGE  TOOLS  43 

gouge  is  placed  flat  against  this  surface  and  moved  back  and  forth 
over  the  wire  edge.  Some  prefer  to  strop  the  bevel  of  wood- 
cutting tools  on  a  strip  of  leather  glued  to  wood.  This  is  seldom 
done  by  the  mechanic. 

The  skew  chisels  are  so  ground  that  the  angle  of  the  cutting 
edge  with  the  length  of  the  tool  is  between  45°  and  60°,  varying 


/\    /  Fig.  20 

>o°      7 

Fig.  19 

with  the  wood  and  the  nature  of  the  work.  See  a,  Fig.  19.  The 
angle  between  the  bevels  in  b,  Fig.  19,  should  be  about  25°.  The 
skew  chisels  are  ground  like  other  beveled  tools,  described  above,  and 
are  whetted  on  each  bevel.  It  is  important  to  keep  each  bevel  a  per- 
fect .plane  surface  and,  for  that  reason,  the  bevel  is  laid  flat  on  the 
oilstone  in  whetting  and  is  not  raised  as  was  the  plane-iron  in  Fig.  16. 

Scraping  tools  are  ground  so  that  the  bevel  makes  an  angle  of 
approximately  45°  with  the  length  of  the  tool 
as  in  Fig.  20.  f  "^ 

The  parting  tool,  Fig.  21,  has  an  angle  of      t     f  v^ 

about  50°  between  the  beveled  edges.  ?      \         —^^ 

44.     The  Draw-knife  is  hard  to  hold,  in        9f\.  \  " 
grinding,  because  of  the  handles,  but  should  ^. 

be  held  on  the  stone  as  explained  for  plane- 
irons  and  chisels.  The  whetting  can  be  done  very  handily  by 
holding  the  draw-knife,  back  down,  on  the  bench  with  the  beveled 
side  next  to  you.  It  is  held  there  by  the  left  hand  while  the 
right  grasps  the  oilstone  and  applies  it  to  the  beveled  edge  as 
shown  in  Fig.  22. 


44 


SCHOOL  SHOP  MAINTENANCE 


45.  Spokeshave  Blades,  being  so  short,  are  inconvenient  to 
handle  and  a  holder  like  that  in  Fig.  23  is  handy.  Dotted  lines 
represent  the  blade  in  place  for  sharpening.  It  is  ground  and 
whetted  like  other  beveled  tools. 


Fig.  23 


Fig.  22 


46.  The  Outside  Gouge  is  given  a  rotary  motion  in  grinding 
as  is  the  turning  gouge,  but  unlike  the  latter  it  has  a  square  end 
rather  than  a  semi-circular  one,  when  viewed  at  right  angles  to  its 
length.     The  slip-stone  must  be  used  to  remove  the  wire  edge  in 
the  same  manner  as  for  the  turning  gouge. 

47.  The  Inside  Gouge,  so  named  because  the  bevel  is  on  the 
the  inside  curve,  cannot  be  ground  on  an  ordinary  emery  wheel  or 
grindstone.     A  device  that  works  satisfactorily  can  be  made  on  a 
wood  lathe  and  similar  in  shape  to  Fig.  24.     The  small  tapered 
end    should    fit    the    tapered    opening    for 

the  live  center.  After  it  is  turned  smooth 
from  some  fine  grained  wood  such  as 
maple,  it  is  coated  with  a  thin  coat  of  ^ig  24 

glue  and  dipped  in  flower-of-emery  and 
allowed  to  take  up  all  the  emery  possible.  After  thoroly  dry- 
ing, it  is  again  dipped.  This  is  repeated  until  three  or  four  coats 
of  the  powdered  emery  are  on  it.  The  cone  shape  allows  for  the 
grinding  of  different  sizes  of  gouges.  Insida  gouges  are  whetted 
with  a  slip-stone  on  the  bevel  after  being  ground  and  a  slip- 


FITTING  EDGE  TOOLS  45 

stone  is  rubbed  flat  on  the  outside  of  the  gouge  to  remove  the 
wire  edge. 

48.  Cabinet  Scrapers  do  their  work  by  means  of  a  turned-over 
corner  or  arris.  The  scraper  is  fastened  in  a  vise  and  filed  flat, 
crosswise  of  the  edge,  and  slightly  rounding  lengthwise,  so  that 
the  corners  will  not  dig.  It  is  then  draw-filed  as  in  Fig.  25,  with 
one  hand  grasping  the  end  of  the  file  and  the  other  the  handle, 
causing  the  file  to  move  in  the  direction  indicated  by  the  arrows. 
The  edge  is  then  whetted  keen  on  an  oilstone  as  shown  in  Fig.  26, 


Fig.  26 
Fig.  25 

and  the  wire  edge,  from  grinding,  is  removed  by  whetting  slightly 
the  sides  close  to  the  filed  edge.  The  scraper  should  lie  flat  on 
its  side  in  this  operation.  It  should  now  have  a  square-cornered 
edge  free  from  roughness.  The  wire  edge  desired  is  obtained  by 
rubbing  a  burnisher  over  the  corner  as  shown  in  Fig.  27.  The 
scraper  is  held  firmly  on  the  bench  with  the  edge  being  sharpened 
perpendicular  to  the  bench.  The  burnisher  should  be  held  with 
the  point  down,  making  a  right  angle  with  the  scraper,  like  a,  Fig. 
28,  at  first,  an  angle  like  that  at  b  next,  and  finishing  with  the  angle 
at  c.  This  angle  should  be  different  from  the  first  by  not  more 
than  15°.  Turning  the  edge  too  far  causes  it  not  to  "bite"  or 
take  hold  of  the  wood  as  it  should.  When  the  edge  has  been 
turned  too  far,  it  can  be  raised  by  running  the  point  of  the  burnisher 
along  under  the  turned  edge.  A  burnisher  must  be  hard  enough 
not  to  be  scratched  by  the  scraper.  A  good  one  can  be  made  by 
grinding  a  round  file  smooth  and  sharpening  the  end.  A  scraper 


46 


SCHOOL  SHOP  MAINTENANCE 


need  not  be  filed  every  time  it  fails  to  cut  well,  but  should  have 
more  of  the  edge  turned. 

49.  Planer  and  Jointer  Knives  should  be  ground  on  an  auto- 
matic grinder,  where  possible,  as  the  cutting  edges  should  be 
straight  and  this  condition  is  difficult  to  obtain  by  holding  them 


BENCH 


Fig.  27 


Fig.  23 


by  hand  against  an  ordinary  emery  wheel  or  grindstone.  The 
angle  of  the  bevel  with  the  side  of  the  blade  should  be  about  35°. 
In  using  an  automatic  grinder,  care  should  be  taken  that  the  water 
is  turned  on  to  avoid  burning  the  edge.  After  grinding,  the  bevel 
is  whetted  on  an  oilstone  as  explained  for  the  plane-irons  and 
chisels  in  previous  paragraphs.  Recently,  grinding  devices  for  use 
on  the  jointer  and  surfacer  without  removing  the  knives  have 
been  perfected.  This  method  allows  of  such  a  fine  adjustment  of 
the  knives  as  not  to  be  compared  to  the  older  methods  of  sharpening 
and  setting. 


CHAPTER  VI 

FITTING  SAWS 

50.  Hand  Rip-saw. — The  purpose  of  this  section  is  to  give  the 
procedure  for  keeping  in  order  the  various  saws  ordinarily  found 
in  the  school  shop  where  the  number  and  variety  is  not  such  as  to 
require  the  services  of  special  saw-fitting  machinery. 

The  beginner  who  is  trying  to  learn  to  fit  saws  properly  should 
start  with  a  rather  coarse-toothed,  hand  rip-saw  having  about  four 


Fig.  29 


Fig,  30 


or  five  points  to  the  inch;  not  an  old  one  with  uneven  and  poorly 
formed  teeth,  but  one  having  properly  shaped  teeth.  It  is  no  little 
trick  to  fit  a  saw  properly  and  the  learner  should  have  correctly 
formed  teeth  to  work  on  first,  his  aim  being  to  maintain  this  form 
as  he  acquires  skill  in  the  handling  of  his  file.  Perhaps  a  still 
better  way  is  to  give  the  beginner  a  strip  of  soft  steel  about  Vf6" 
thick,  I"  wide  and  6"  long  and  show  him  the  proper  lay-out  for  a 
rip-saw  tooth  of  any  number  of  points  to  the  inch,  for  the  form  is 
the  same  regardless  of  the  number  of  points  to  the  inch.  Have 
him  then  lay  out  on  the  edge  of  the  strip  teeth  with  points  J4" 
apart,  and  corresponding  in  form  to  the  diagram,  Fig.  29,  the 
arrow  of  which  indicates  the  direction  of  the  cutting  stroke. 
Notice  that  the  front  of  the  tooth  is  at  right  angles  to  a  line  run- 
ning thru  the  points  of  the  teeth,  and  that  the  angle,  between 
the  back  and  front  edges  of  a  tooth,  is  60°,  and  also  that  the  tooth 

47 


48  SCHOOL  SHOP  MAINTENANCE 

is  made  by  filing  square  across  the  blade  so  that  there  is  no  bevel 
or  fleam,  as  in  the  crossscut-saw  illustrated  in  Fig.  30.  In  laying 
out  the  teeth,  use  a  bevel,  try-square  and  scribe,  and  make  the 
marks  strong  enough  to  be  seen  plainly.  It  should  not  be  necessary 
to  lay  them  out  on  both  sides  of  the  strip.  Place  the  strips  in  the 
vise,  as  low  as  possible  and  still  have  clearance 
for  the  file.  If  no  saw  clamp  is  at  hand,  a 
very  serviceable  one  can  be  made  of  two 
strips  of  J/g"  hard  wood,  about  2"  wide,  which 
can  be  clamped  close  to  the  teeth  in  an  ordi- 
1  '  '  "  nary  bench  or  machinist's  vise.  The  outside 
edges,  at  the  top  of  the  strips,  should  be 
beveled  to  allow  clearance  for  the  file. 

For  filing  such  large  teeth,  a  slim  taper  file 
about  1"  long  should  be  used.     It  should  have 
a  handle  on  it.     With  the  handle  in  the  right 
Fig  31  hand  and  the  left  holding  the  tip  of  the  file, 

assume  such  a  position  that  the  file  moves  in 
a  direction  perpendicular  to  the  side  of  the  strip  and  at  right 
angles  to  a  line  lengthwise  of  it  thru  the  points  of  the  teeth,  Fig.  31. 
A  file  is  made  to  cut  on  the  pushing  stroke  only.  It  should  be 
slightly  freed  from  contact  with  the  teeth  on  the  return  stroke. 
With  a  number  of  firm  strokes,  file  out  the  metal  between  the 
teeth  just  to  the  scratch  mark. 

The  first  operation,  in  fitting  a  saw,  is  to  joint  it  if  necessary. 
Then  it  is  set  and  after  that  filed.  Of  course  the  ordinary  pro- 
cedure could  not  be  followed  in  this  exercise.  When  the  learner 
has  carefully  filed  the  teeth  the  full  length  of  the  strip,  he  has  a 
fair  idea  of  how  the  teeth  should  appear  and,  furthermore,  he  has 
acquired  some  skill  in  manipulating  the  file. 

The  next  step  for  the  learner  is  to  try  to  get  this  same  form  in 
the  teeth  of  an  actual  saw.  First,  sight  lengthwise  of  the  saw  at 
the  teeth  to  see  if  they  are  all  in  line,  and  if  the  line  is  a  slightly 
crowning  one,  with  the  middle  portion  about  J-g"  higher  than  at 
the  ends.  If  the  teeth  are  not  even  or  the  line  is  not  crowned 


FITTING  SAWS  49 

properly,  the  high  ones  must  be  filed  until  all  are  in  line.  This 
process  is  called  jointing.  For  this  purpose  a  10"  flat  file  should 
be  used.  With  the  saw  fastened  in  a  clamp,  the  file  is  laid  flat  on 
the  points  of  the  teeth  and,  with  the  fingers  lightly  rubbing  the 
sides  of  the  saw  to  keep  the  file  from  rolling  sideways,  it  is  pushed 
forward  over  the  teeth.  This  is  repeated  in  places  where  needed 
until  the  shortest  tooth  is  just  tipped  or  flattened  on  the  top  and 
the  crown  is  perfect.  As  it  is  quite  difficult  for  a  beginner  to  hold  the 
file  exactly  horizontal  at  all  times,  it  is  desirable  to  use  a  jointer. 
There  are  several  commercial  styles  on  the  market,  and  one  can 
be  made  like  that  shown  in  Fig.  32.  Notice  the  clearance  made  for 
the  teeth  in  the  block  close  to  the  file.  Care  should  be  taken  that 
the  file  is  set  in  the  block  at  right  angles  to  the  face  of  the  latter. 
The  next  operation,  which  is  setting,  means  the  bending  of 
every  alternate  tooth  slightly  to  one  side  and  the  remaining  teeth 
to  the  opposite  side  of  the  saw,  the  purpose  being  to  cause  the  teeth 
to  cut  a  groove  wide  enough  so  that  the  blade  of  the  saw  will  pass 
thru  without  being  pinched  by  the  wood.  A  common  fault  is 
that  of  putting  too  much  set  in  the  teeth,  thus  causing  them  to 
break.  Teeth  should  always  be  set  to  the  same  side  as 
they  were  previously.  Also,  all  of  the  bend  or  set  should  j-g-| 
be  in  the  upper  half  of  the  teeth  and  not  in  the  base,  else  «~U> 
they  are  liable  to  break.  The  teeth  should  be  set  only 
enough  to  allow  freedom  of  the  blade  in  passing  thru  the 
groove  made  by  teeth.  The  least  set  that  is  possible,  and 
yet  have  a  free  saw,  the  better.  There  are  a  number  of 
ways  of  setting  teeth.  One  method  is  to  bend  them 


with  a  tap  of  a  hammer  over  a  stake  or  small  anvil  made     Fig.  32 
for  the  purpose  and  held  in  a  vise.    Another  method  is 
that  of  swage  setting  where  a  swage  is  driven  on  the  points  of 
the  teeth  causing  the  points  to  spread  or  flare.     In  this  case,  all 
are  swaged  alike  and  not  bent  to  the  side  as  in  setting. 

The  more  common  method  is  that  of  using  the  spring  saw  set. 
It  is  not  feasible  to  describe  the  various  styles,  but  most  of  them 
have  a  beveled  disc  or  a  sliding  bar  with  a  bevel.  These  pieces 


50  SCHOOL  SHOP  MAINTENANCE 

are  so  adjusted  that  the  bend  will  come  in  the  right  place  in  the 

tooth  according  to  the  size  being  set.     Some  sets  have  numbers 

on  the  discs  corresponding  to  the  points  per  inch.     There  is  also 

an  adjusting  screw  that  presses  against  the  side  of  the  saw  and 

allows  variation  in  the  amount  the  tooth  is  bent  to  the  side.     The 

beveled  piece  simply  determines  the  distance  from  the  point  that 

the  tooth  is  bent.     For  ordinary  dry  woods,  1-100"  bend  to  each 

j^_^___^__^      side  of  the  saw  should  be  sufficient.     Soft  or  damp 

a  woods   require   more   set.     Fig.   33   illustrates   the 

CJE^HdZ?     effect  of  setting  the  teeth  of  a  saw.     In  this  sketch, 

.  the  set  is  exaggerated  for  sake  of  illustration.    Swage 

set  is  shown  by  a;  spring  set  by  b.     Every  alternate 

tooth  is  set  to  one  side  of  the  saw;  the  saw  is  then  reversed  and 

the  remaining  teeth  are  set  to  the  opposite  side. 

The  saw  having  been  properly  set,  the  next  step  is  to  file  it. 
As  in  setting,  every  alternate  tooth  should  be  worked  from  one  side 
and  the  remaining  teeth  from  the  opposite  side.  The  bulk  of  the 
filing  should  be  done  on  the  front  edge  of  the  teeth  and  on  those 
teeth  that  point  away  from  the  operator,  in  order  to  avoid  chatter- 
ing of  the  saw,  with  injury  resulting  to  both  the  saw  and  file.  File 
each  tooth  nearly,  but  not  quite,  to  a  point.  They  will  be  brought 
to  a  point  later,  when  filing  the  remaining  teeth  from  the  opposite 
side.  Some  call  the  fitting  completed  when  the  teeth  are  all  filed 
to  a  point.  Others  prefer  to  side-dress  the  saw.  This  consists  in 
laying  the  saw  flat  on  the  table  or  bench  and  rubbing  an  oilstone 
or  fine  file  lightly  over  the  sides  of  the  teeth  to  remove  the  burr 
left  by  the  file.  It  is  certain  that  a  smoother  cut  is  made  by  a  side- 
dressed  saw. 

The  rip-saw  is  used  lengthwise  of  a  board  and  the  action  of  its 
teeth  are  like  a  number  of  tiny  chisels,  each  chipping  a  portion  from 
the  end  of  the  fibre  of  wood.  The  crosscut-saw  is  used  to  cut 
across  the  fibre  of  the  wood  and  its  action  is  different.  Instead  of 
cutting  off  ends  of  fibres,  it  severs  them  at  each  side  of  the  saw. 
One  set  of  teeth  cuts  them  on  one  side  and  the  opposite  set  on  the 
other  side.  For  this  reason,  the  teeth  are  brought  to  a  sharp 


FITTING  SAWS  51 

edge  by  filing  a  fleam  or  bevel  on  them.  This  is  shown  in  a, 
Fig.  34.  These  bevels  are  filed  on  the  inside  edges  of  each  tooth. 
The  bevel  of  the  front  edge  of  the  tooth  should  make  an  angle  of 
about  45  degrees  with  the  plane  of  the  saw  blade.  The  angle  of 
the  bevel  in  back  varies  with  the  nature  of  the  work  to  be  done. 
Fig.  34,  a,  shows  a  tooth  of  a  5j^-point  hand-saw  for  cutting 
soft  wood.  The  bevel  on  the  front  is  the  same  as  that  on  the 
back.  In  b  is  shown  the  tooth  of  a  7-point  saw,  for  medium  hard 
wood,  with  less  fleam  on  the  back,  while  c  shows  a  10-point  tooth 
for  hard  wood.  There  is  no  bevel  on  the  back.  In  general,  it  can 
be  said  that  the  harder  the  wood  the  smaller  the  tooth  and  the 
less  the  bevel  on  the  back  of  the  tooth.  Pitch  is  a  term  used  quite 
ambiguously  in  connection  with  saws.  In  Figs.  35  and  36,  this 
is  represented  by  the  difference  between  angles  a  and  a  respectively. 
In  Fig.  35  the  angles  a  and  b  are  the  same  and  the  tooth  is  said  to 
have  no  pitch.  In  Fig.  36  the  point  of  the  tooth  has  been  pitched 
ahead  6  degrees  from  its  position  in  Fig.  35  where  the  front  edge 
makes  an  angle  of  60  degrees  with  the  line  thru  the  teeth.  This 
angle  varies  according  to  the  work  to  be  done,  hard  woods  requiring 
less  pitch  than  soft. 

51.  Hand  Crosscut-Saw. — The  hand  crosscut-saw  is  jointed 
and  set  as  was  the  rip-saw,  but  it 
is  not  filed  in  the  same  manner  as  /K  K 
the  rip-saw.  It  will  be  reraem-  ^  Y  '  ' 
bered  that  in  filing  the  latter,  the 
file  was  held  horizontally  and  at 
right  angles  to  the  length  of  the  saw  or,  in  other  words,  square 
across  the  saw.  For  the  crosscut-saw,  the  file  should  be  so  placed 
that  it  makes  an  angle  of  approximately  45  degrees  with  a  line 
thru  the  teeth  and  at  the  same  time  should  be  parallel  to  the  per- 
pendicular to  the  side  of  the  saw,  or  horizontal.  In  making  the 
above  angle  of  45  degrees,  the  handle  of  the  file  should  swing 
towards  the  handle  of  the  saw  so  that  the  file  is  pushed  towards 
the  small  end  of  the  saw  and  works  on  the  front  edge  of  those 
teeth  which  point  away  from  the  operator.  As  in  the  case  of  the 


52  SCHOOL  SHOP  MAINTENANCE 

rip-saw,  every  alternate  tooth  is  filed  from  one  side;  then  the  saw 
is  reversed  in  the  clamp,  and  the  remaining  teeth  are  filed  from  the 
opposite  side  of  the  blade.  The  bulk  of  the  filing  should  be  done 
on  the  front  edge  of  the  teeth  and  on  those  teeth  which  point 
away  from  the  operator,  in  order  to  avoid  chattering.  For  8,  7,  6 
and  5-point  saws  use  a  6"  slim  taper,  three-cornered  file,  and  for 
9  to  12-point  saws  use  a  5"  slim  taper  file. 


'66°  to  78° 

Fig.  35  Fig.  36 

A  circle,  turning  or  web  saw  is  usually  filed  like  a  rip-saw. 

52.  Key-hole  Saw. — A  key-hole  saw  is  filed  in  a  manner  which 
is  about  half  rip  and  half  crosscut.     That  is,  the  tooth  is  pitched 
more  than  a  crosscut,  but  not  as  much  as  a  rip-saw  tooth.     The 
front  of  each  tooth  should  make  an  angle  of  about  70  degrees  with 
the  line  thru  the  points.     The  bevel  or  fleam  is  not  so  acute  as  that 
of  a  crosscut-saw,  yet  the  tooth  is  not  square  in  front  like  a  rip-saw. 

53.  Mitre-  and  Back-Saws. — These  saws  have  crosscut  teeth 
but,  because  of  the  fineness  of  the  teeth,  require  much  care.     A 
cant,  safe-back  file  should  be  used. 

54.  Band-Saws. — Band-saws  have  a  rip-saw  tooth,  the  proper 
shape  of  which  is  shown  in  Fig.  37.     If  fitted  by  hand,  they  should 
receive  the  same  treatment  as  a  hand  rip-saw,  but  it  is  a  long  task. 
There  are  a  number  of  good  band-saw  fitting  machines  on  the 
market  that  file  and  set  very  quickly,  filing  a  saw  in  from  ten  to 
fifteen  minutes  with  little  attention  after  the  first  adjustment  is 
made  and  the  machine  started.     They  are  not  difficult  to  learn 
to  operate.     The  principle  on  which  they  work  is  the  same,  tho 
the  construction  of  the  machines  varies  considerably.     The  saw 
runs  over  pulleys  and  passes  thru  a  guide  on  the  machine,     It  is 
moved  thru  the  guide  to  receive  the  stroke  of  the  file  by  a  plunger 


FITTING  SAWS 


53 


Fig.  37 


finger,  usually  working  on  the  tooth  adjacent  to  the  one  being 
filed.  An  ordinary  slim  taper  file  is  hung  on  two  arms  operated 
by  an  eccentric  or  cam  that  gives  a  motion  very  similar  to  that  of 
the  human  hand.  All  the  teeth  are  filed  from  one  side  of  the  saw. 
The  plunger  and  file  are  adjustable  to  various 
sizes  of  teeth  and  saws. 

55.  Circular  Rip-Saws. —  In  circular  rip- 
saws, the  hook  or  pitch,  and  the  size  and 
shape  of  the  gullet,  or  bottom  of  the  teeth, 
are  important.  An  insufficient  amount  of  hook  causes  the  teeth 
to  scrape  and  tear  the  wood;  the  saw  requires  more  power;  it  cuts 
slower  and  gets  dull  more  quickly.  Too  much  hook  weakens  the 
teeth  and  causes  them  to  dodge  or  break.  The  shape  of  the  gullet 
should  be  round  to  allow  room  for  the  shavings  and  saw-dust 
and,  at  the  same  time,  to  strengthen  the  base  of  the  tooth.  A 
square  corner  will  be  liable  to  cause  a  crack  in  the  saw  at  the  corner. 
A  well  formed  tooth  is  shown  in  Fig.  38.  The  distance  a  is  broad 
for  strength.  The  gullet  b  is  round  and  will  hold  sufficient  saw- 
dust to  keep  the  saw  from  choking.  In  Fig.  39,  the  gullet  b  is 
too  small.  The  dotted  lines  show  where  it  should  have  been  filed. 


Fig.  38 


Fig.  39 


Fig.  40  shows  how  they  are  often  filed.  A  tooth  like  this  could 
not  possibly  cut  and  remove  the  saw  dust  properly.  It  would 
furthermore  be  very  liable  to  crack  as  shown  in  the  illustration. 
Fig.  41  shows  the  lay-out  for  the  teeth.  Notice  that  the  front 
of  the  tooth,  if  continued,  would  make  a  tangent  with  circle  A, 
the  diameter  of  which  is  one-half  that  of  the  saw.  There  is  a 
difference  of  opinion  as  to  whether  the  back  of  the  tooth  should 


54 


SCHOOL  SHOP  MAINTENANCE 


be  filed  any  or  not.  The  argument  for  not  doing  so  would  seem 
to  be  the  best.  If  the  tooth  is  filed  on  the  front  only,  different 
filings  will  cause  the  tooth  to  appear  in  the  positions  shown  by  dotted 
lines  in  Fig.  41,  and  if  the  line  of  the  front  of  the  tooth  is  kept  tan- 


Fig.  41 


Fig.  40 

gent  to  circle  A  at 
each  filing,  the  shape 
will  be  kept  constant. 
If,  however,  the  back 
of  the  tooth  is  filed 
near  the  point,  it  will 
be  more  difficult  to 
keep  this  same  shape. 

The  first  step,  in  fitting  a  circular  saw,  is  to  see  if  it  is  round. 
It  can  be  made  so  by  lowering  the  saw  or  raising  the  table  until 
the  saw  rises  just  above  the  latter.  By  holding  a  piece  of  an  old 
emery  wheel  on  the  table  and  pushing  it  gently  against  the  saw 
while  in  motion,  the  points  of  the  high  teeth  are  ground  down  in 
line  with  the  others.  No  more  of  the  points  should  be  ground  off 
than  necessary  to  bring  all  the  teeth  in  line.  Remove  the  saw 
from  the  arbor  and  fasten  it  in  a  saw  clamp.  Very  good  clamps 
can  be  purchased  which  tilt  at  different  angles  to  suit  the  operator's 
convenience.  A  good  one  can  be  made  of  a  !}/£"  plank  of  the  proper 
length  to  reach  from  the  floor  to  the  level  at  which  the  filer  desires 
to  work.  There  should  be  a  slot  near  the  top  of  the  plank  fitted 
with  a  bolt  on  which  the  saw  should  be  hung  and  drawn  tightly 
against  the  plank  by  a  large  washer  or  another  piece  of  plank. 
The  slot  permits  of  raising  and  lowering  the  bolt  to  accommodate 
different  saws. 


FITTING  SAWS  55 

In  order  to  keep  the  teeth  uniform,  a  template  can  be  made 
from  a  piece  of  brass  as  shown  in  Fig.  42.  A  file,  with  a  round 
edge,  should  be  used  for  filing,  as  one  with  square  edges  would 
make  corners  in  the  gullets.  The  teeth  should  be  filed  square 
across  the  front  edge  and  square  across  the  back  except  for  the 
upper  half  near  the  point  which  should  be  slightly  beveled,  the 
highest  portion  being  on  that  side  towards  which  the  tooth  is 
bent.  Often,  the  mistake  is  made  of  beveling  the  front  as  well 
as  the  back.  This  causes  vibrations  and  "runs."  If  an  emery  wheel 
of  the  proper  shape  is  available,  the  gullets  can  be  rounded  on 
that.  A  round  file  can  also  be  used  for  this  purpose. 

Having  been  filed,  the  teeth  should  now  be  set.  In  this  con- 
nection it  might  be  noted  that  it  is  perhaps  justifiable  to  insist 
that  teeth  be  set  before  being  filed,  for  the  process  of  setting  is 
liable  to  injure  the  edge  of  a  keen  tooth.  Every  alternate  tooth 
should  be  bent  to  one  side  and  the  remaining  teeth  to  the  opposite 
side.  This  can  be  done  in  several  ways.  A  mechanic,  if  not 
particular,  files  a  small  chamfer  on  the  edge  of  his  saw  table,  and 
laying  the  saw  on  the  table,  strikes  each  tooth  a  light  blow,  bending 
it  over  the  chamfer.  This  is  a  make- 
shift method  and  does  not  insure  an 
even  setting.  If  the  teeth  are  not 
evenly  set  the  cut  is  not  as  smooth, 
and,  as  some  teeth  would  have  to  do 
more  than  their  share  of  the  work,  ^  • 

they  become  dull  quicker  than  if  they      v  \ 

were  assisted   by  the  proper  working        \_' ,"--*__^ — •-* 

of  the  faulty  teeth.     A  setting  stake  Fig.  42 

can  be  purchased  which  has  a  beveled 

disc  anvil  over  which  the  teeth  are  bent.     The  amount  of  set  is 

adjustable.     There  are  also  spring  saw-sets,  larger  than  those  for 

hand-saws,  but  working  on  the  same  principle. 

After  setting,  the  teeth  should  b3  side-dressed  with  a  flat  fib 
until  the  amount  of  set  is  the  same  on  all  teeth.  This  is  determined 
by  some  gage.  Fig.  43  shows  a  home  made  gage  that  is  good. 


56 


SCHOOL  SHOP  MAINTENANCE 


The  screws  a,  a,  a  project  equally  thru  the  wood.  Screw  b  is 
adjusted  so  as  to  make  c  the  distance  from  screw  b  to  side  of  saw, 
equal  to  the  set  desired.  A  circular  saw  should  have  set  no  farther 
down  the  teeth  than  necessary  to  make  it  run  free  and  the  amount 
that  the  teeth  bend  to  each  side  of  the  saw  should  be  about  %%' '. 
5  6.  Circular  Crosscut-Saws. — Circular  crosscut-saws  are  fitted 
in  much  the  same  manner  as  the  rip-saws.  The  teeth,  however, 


Fig.  43 


Fig.  44 


are  different  in  form  and  have  more  bevel  or  fleam  on  the  back  and 
front.  Fig.  44  shows  crosscut  teeth.  The  gullet  should  be  round 
and  the  bevel  should  not  reach  to  it,  but  about  half-way  down. 
A,  Fig.  44  shows  a  tooth  for  soft  wood  and  B  one  for  hard  wood. 
In  using  an  emery  wheel  for  gumming  or  rounding  the  gullets,  care 
should  be  taken  to  prevent  the  saw  from  being  heated  to  a  blue 
color.  It  is  better,  in  this  process,  to  work  around  the  saw  a 
number  of  times,  cutting  a  small  amount  each  time,  and  thus 
prevent  over-heating  the  teeth. 

If  a  crack  forms  near  the  rim  of  the  saw,  it  can  be  kept  from 
growing  longer  by  drilling  a  small  hole  at  the  base  of  the  crack. 

Tho  it  may  cause  temporary  delay,  much  time  is  gained  in 
the  end  by  keeping  the  saws  in  good  condition  all  the  time.  Touch- 
ing up  the  teeth  often  is  a  small  job,  but  to  wait  until  they  become 
very  dull  makes  a  laborious  job  of  the  fitting. 


CHAPTER  VII 
BRAZING  BAND-SAWS 

57.  Brazing. — A  good  joining  of  band-saw  blades  by  brazing 
is  a  knack  not  difficult  to  acquire,  and  one  needs  only  to  work 
carefully  and  accurately.  Perhaps  the  best  way  to  learn  is  to 
take  short,  broken  pieces  of  a  band-saw  blade  and  practice  on 
these,  making  a  number  of  joints  until  always  sure  of  a  good 
braze.  The  beginner  should  start  on  a  narrow  blade,  about  %" 
or  so  wide,  and  gradually  try  wider  ones.  As  it  is  probably  easier 
to  make  a  two-tooth  lap,  i.  e.,  lapping  the  ends  a  distance  equal 
in  length  to  two  teeth,  the  novice  should  attempt  this  first,  but 
a  one-tooth  lap  is  preferable  on  saws  up  to  Y%  or  %"  wide,  as  the 
strain  in  passing  over  the  wheels  of  the  saw  frame  is  less  liable  to 
part  it. 

The  first  operation  in  brazing  is  to  examine  the  blade  and  see 
how  much  filing  is  needed.  The  lap  or  scarf  will  look  like  Fig.  45 
and  should  b3  so  made  that  the  "set"  of  the  teeth  where  the  ends 
join  will  match.  If  care  is  not 

taken  in  this  particular,  when      P*^ — ^S^^>4^^I^^r^^J^ 
the  saw  is  set  later  on  there      \  j  I 


will  be  two  teeth  next  to  each 
other  which  are  set  to  the 
same  side,  and  unless  the 
operator  has  kept  this  in  mind 
and  started  setting  on  the  lap  Fig.  45 

and  finished  at  the  lap,  there 

will  be  trouble,  for  he  will  be  setting  a  number  of  teeth  to  the 
opposite  side  from  which  they  have  been  set  before  and  this  is 
liable  to  break  them.  A  saw  should  have  an  even  number  of  teeth 
in  order  to  have  them  set  alternately  to  the  right  and  left  thruout 
the  length  of  the  saw.  After  deciding  where  the  joint  is  to  be  made, 

57 


58 


SCHOOL  SHOP  MAINTENANCE 


it  is  best  to  first  file  the  ends  square  with  the  sides;  then  each  end 
can  be  placed  en  a  strip  of  hard  wood,  Fig.  46,  and  held  in  place 
by  a  small  clamp.  The  strip  of  wood  is  then  fastened  tightly  in 
a  vise  and  the  end  scarfed  to  appear  like  A,  Fig.  45.  One  scarf 
will  be  on  one  side  of  the  blade  and  the  other  on  the  opposite  side. 
A  flat  hand  or  mill  file  should  be  used  for  this  purpose.  The  laps 
should  be  perfectly  flat  surfaces  and  should  fit  each  other  nicely. 
They  should  be  filed  to  almost  a  knife  edge  at  the  ends.  Some 

prefer  to  draw-file  the 
laps  as  a  finishing 
touch.  After  being 
sure  that  the  scarfs 
bear  on  each  other 
evenly,  carefully  clean 
any  grease  or  dirt  from 
the  filed  surfaces.  This 
can  be  done  with  muri- 
atic acid,  slaked  lime 
or  a  compound  made 
purposely.  It  is  very 
essential  for  a  good 
braze  to  have  clean  surfaces.  Now  put  the  saw  in  the  brazing 
clamp,  Fig.  47,  being  sure  that  the  edge,  opposite  the  teeth,  makes 
a  good  contact  with  the  straight  edge  on  the  clamp  and  that  the 
laps  and  teeth  match  up.  A  slight  allowance  can  be  made  for 
expansion  of  the  saw  upon  being  heated.  When  the  blade  is  in 
proper  position  with  laps  over  the  center  of  the  opening  in  the 
clamp,  fasten  it  there  with  the  clamp  screws,  not  too  tightly,  how- 
ever, for  the  saw  expands  on  heating  and  if  not  allowed  to  move 
under  screws  a  trifle,  it  is  liable  to  buckle  near  the  joint.  It  could 
be  straightened,  but  it  is  not  necessary  to  have  it  buckle  if  the 
tension  on  it  is  proper. 

There  are  at  least  three  ways  in  which  the  blades  can  be  heated 
and  a  good  braze  made  for  practice.  The  author  has  his  students 
use  all  three  methods,  as  the  most  desirable  appliances  are  not 


Fig.  4G 


BRAZING  BAND-SAWS 


59 


always  at  hand.  For  the  narrower  saws,  tongs  will  do,  but  for 
wider  saws  a  heavier  clamp  and  one  including  heating  irons  is 
necessary.  The  principle,  however,  is  the  same.  The  treatment 
for  the  narrower  blades  and  tongs  is  as  follows:  After  the  saw  is 
in  place  in  the  clamp,  a  flux  is  applied  to  the  scarfs.  Lump  borax 
works  very  nicely  and  is  prepared  by  pulverizing,  only  as  needed, 
and  then  mixing  to  a  paste  with  water.  Also  there  are  compounds 
prepared  expressly  for  this  purpose.  A  piece  of  silver  solder,  ths 


Fig.  47 

size  of  the  laps,  is  cut  and  cleaned,  as  was  the  scarf,  and  placed 
between  the  laps.  Two  pairs  of  tongs  should  be  heated,  one  to  a 
bright  red  heat — almost  a  yellow,  but  not  a  white  heat,  and  the 
other  to  a  dull  red  heat.  Take  the  hottest  tongs  from  the  fire  and 
scrape  the  inside  surfaces  clean  with  an  old  file,  edga  of  a  square 
iron  or  something  similar,  and  then  apply  the  tongs  quickly  to 
the  joint,  clamping  it  tight.  The  tongs  should  be  a  bright  red 
color  when  applied  or  the  solder  will  not  melt  and  run  out  properly. 
When  the  solder  can  be  seen  to  melt  and  run,  the  tongs  should 
be  carefully  removed  and  dull  red  ones  very  quickly  applied  in 
their  place.  This  change  must  be  made  quickly  or  the  joint  will 
open.  The  second  pair  of  tongs  should  be  left  on  until  they  are 


60  SCHOOL  SHOP  MAINTENANCE 

black.  If  only  one  pair  of  tongs  is  available,  it  can  be  heated  to  a 
bright  red,  and  left  on  the  joint  until  black.  Sometimes  the  handles 
get  pretty  hot  by  that  time  and  the  temper  of  the  saw  is  then 
liable  to  be  injured,  so  a  second  pair  is  more  advisable. 

When  the  saw. is  cold  enough  to  handle,  file  the  solder  out  of 
the  joints,  clamp  the  saw  on  the  block  of  wood  used  for  making 
scarfs  and  dress  each  side  of  the  joint  with  a  file  until  it  is  the 
same  thickness  as  the  remainder  of  saw. 

A  second  method  is  that  of  heating  the  joint  with  a  blow  torch 
to  a  bright  red  heat  or  until  the  solder  melts  and  runs,  and  then 
clamping  it  tight  with  a  pair  of  tongs  heated  to  a  dull  red.  This 
method  is  often  used  where  no  forge  is  handy.  The  tongs  can  be 
heated  a  trifle  hotter  than  necessary  with  the  blow  torch  before 
heating  the  joint  and  when  the  joint  is  hot  they  will  have  cooled 
sufficiently  to  be  of  the  right  temperature. 

In  the  third  case,  a  bunsen  burner  is  used  to  heat  the  blade. 
This  is,  of  course,  a  slower  process,  but  will  answer  the  purpose 
if  other  equipment  is  not  available.  The  tongs  should  be  heated 
first,  as  when  the  blow  torch  is  used.  It  may  be  necessary  to 
use  two  burners  in  order  to  get  the  tongs  hot  enough.  Be  sure  to 
allow  for  the  cooling  of  the  tongs  while  the  joint  is  being  heated. 

When  brazing  with  the  bunsen  burner  or  blow  torch,  it  may 
be  found  advantageous  to  wrap  fine  wire  tightly  around  the  laps 
after  the  solder  is  in  place.  Twist  the  ends  of  the  wire  at  the  side 
where  they  will  not  prevent  the  tongs  from  pinching  the  joint 
tightly. 

Where  it  is  necessary  to  braze  saws  wider  than  1",  it  is  advisable 
to  use  a  larger  clamp  fitted  with  two  irons  which  can  be  heated 
and  clamped  in  position  on  each  side  of  the  joint.  These  should 
be  left  there  until  cold.  It  is  difficult  to  get  even  pressure  over 
such  a  large  joint  with  tongs. 


CHAPTER  VIII 
BELTING 

58.  Belt  Comparisons. — There  are  three  kinds  of  belts  in 
common  use;  namely,  leather,  rubber  and  canvas  or  gandy  belts. 
Each  has  it  advantages  and  disadvantages,  and  in  choosing  a 
belt,  one  should  have  in  mind  where  it  is  to  be  used  and  how. 

Leather  belts  are  the  strongest,  wear  the  longest,  stretch  the 
least,  can  be  cut  into  narrower  belts  and  are  not  injured  by  animal 
oils.  However,  the  first  cost  is  the  greatest,  and  they  are  injured 
by  water,  steam,  mineral  oils  and  extreme  cold  or  heat.  They 
are  not  always  uniform  in  thickness,  and  for  that  reason,  stress 
may  not  be  exactly  uniform  thruout  a  leather  belt. 

Rubber  belts  are  uniform  in  thickness,  width  and  strength  and 
make  good  pulley  contact.  Extreme  temperatures  will  not  harm 
them.  They  are  not  as  expensive  as  leather,  as  far  as  first  cost  is 
considered,  and  are  waterproof.  But  they  cannot  be  cut  into  smaller 
belts  to  advantage,  will  not  wear  like  leather  and  stretch  easier. 

Canvas  belts  have  the  lowest  first  cost,  are  strong,  flexible  and 
make  good  contact.  They  are  uniform  in  width  and  thickness  and 
consequently  strength.  They  are  not  injured  by  oils,  greases, 
steam  or  water  and  can  be  run  with  either  side  to  the  pulley. 
They  cannot,  however,  be  cut  up  into  smaller  belts,  and,  if  broken 
or  cut,  easily  fray.  They  stretch  easily  and  shrink  or  expand 
with  changes  of  the  weather. 

If  conditions  are  right  for  leather  belting,  and  the  belt  to  be 
chosen  will  be  subject  to  hard  and  continuous  wear,  the  purchase 
of  a  good  leather  belt  will  undoubtedly  pay  in  the  long  run. 

59.  Choosing  a  Belt. — The  best  grades  of  leather  belting  are 
taken  from  that  part  of  the  hide  which  runs  parallel  to  and  near 
the  back-bone,  and  from  the  tail  to  a  point  just  back  of  the 
shoulders.     It  is  hard  to  judge  a  belt  by  merely  looking  at  it,  but 

61 


62  SCHOOL  SHOP  MAINTENANCE 

in  general  it  is  wise  to  choose  the  one  made  of  the  shortest  laps  or 
pieces.  If  long  pieces  can  be  seen  in  the  make-up  of  the  belt,  it 
can  be  assumed  that  part  of  the  neck  of  the  hide  was  used,  or  else 
parts  farther  removed  from  the  back-bone.  These  parts  are  easily 
stretched.  Some  manufacturers  will  combine  the  poorer  grades 
with  the  best  grade,  putting  the  latter  on  the  outside.  This  makes, 
perhaps,  even  a  poorer  belt  than  if  it  were  made  entirely  of  the 
inferior  grade  of  leather,  for  the  parts  do  not  stretch  alike,  and 
consequently  there  is  an  uneven  stress  thruout  the  length  of  ths 
belt.  The  leather  that  is  strong,  close  of  texture  and  less  easily 
stretched  is  that  part  close  to  the  spine,  and  such  strips  will  be  not 
over  4  ft.  long.  Narrow,  thick  belts  are  generally  more  satis- 
factory than  wide,  thin  ones,  especially  at  high  speeds.  The  latter, 
if  run  fast,  run  in  rolls  or  waves  with  considerable  flapping  on  the 
slack  side.  This  tends  to  wear  the  belt  rapidly.  A  light,  double 
belt  is  considered  better  than  the  same  thickness  in  a  single  belt. 
It  is  not  good  policy  to  use  double  belting  for  twisted  belts  running 
fast,  nor  in  places  where  water  or  oil  come  in  contact  with  it.  It 
is  advisable  to  use  double  belting  on  pulleys  larger  than  twelve 
inches  in  diameter. 

60.  Care  of  Belts. — Leather.  The  life  and  service  of  a  belt 
depends  upon  the  care  it  receives.  Rosin  is  often  used  to  prevent 
the  slipping  of  belts,  but  it  is  injurious  to  the  leather.  Neatsfoot 
oil  (if  not  a  substitute  for  the  real  thing)  is  good.  Boiled  linseed 
oil  gives  good  clinging  qualities.  Castor  oil  does  very  well.  If  a 
belt  becomes  glazed  and  dry,  rub  with  a  cloth  dipped  in  kerosene 
and  apply  a  thin  coat  of  the  following  mixture  to  the  driving  side: 
Two  parts  beef  tallow,  one  part  cod  liver  oil  (by  weight).  Melt 
the  tallow,  and  when  cool  enough  to  insert  the  finger,  stir  into  it 
the  cod  liver  oil.  Continue  stirring  until  cold.  Do  not  allow 
lubricating  oils  to  come  in  contact  with  leather  belts,  if  it  can  be 
avoided.  If  belts  do  become  soaked  with  oil,  pack  in  sawdust, 
wash  in  naphtha  soap  and  apply  the  above  dressing. 

Rubber.  Keep  oils  and  greases  off.  An  occasional  application 
of  the  following  will  add  to  their  life:  Equal  parts  of  red  lead, 


BELTING 


63 


black  lead,  French  yellow,  and  litharge,  mixed  with  boiled  linseed 
oil  and  enough  japan  drier  to  make  it  dry  quickly.  Paint  it  on 
and  give  it  time  to  dry  thoroly. 

Stretching.  A  new  belt  should  be  stretched  before  using.  This 
can  be  done  by  fastening  the  ends  to  the  floor  with  blocks,  and 
raising  the  center  on  blocks  and  leaving  it  thus  for  some  time. 


Fig.  48 

This  should  be  done  before  measuring  for  length  or  joining  ends. 
If  not  stretched,  then  a  belt  should  be  from  one  to  two  inches 
shorter  than  the  actual  measurements  around  the  pulley,  to  allow 
for  the  stretching  which  will  result  when  first  put  to  use.  Never 
"run  on"  a  wide  belt  if  it  can  be  avoided.  Use  a  stretcher  in 
joining  ends,  Fig.  48,  and  lace  or  splice  them  on  the  pulleys.  In 
the  stretcher  shown  in  Fig.  48  two  bolts,  with  nuts  or  winged 
nuts,  fasten  the  pieces  in  each  clamp  tight  against  the  belt.  With 
a  wide  belt  and  a  hard  pull,  it  is  sometimes  necessary  to  drive  two 
nails  thru  each  clamp  and  the  end  of  belt  to  keep  it  from  slipping. 
This  stretcher  can  be  easily  made  of  good  hard  wood  and  threaded 


64 


SCHOOL  SHOP  MAINTENANCE 


rods  or  bolts  of  the  proper  size.  For  belts  of  medium  size  use 
about  1/2"  bolts  and  l^"  maple  strips  for  clamps.  Put  washers 
under  heads  and  nuts  of  all  bolts. 

6 1 .  Applying  Belts  to  Pulleys. — There  is  a  difference  of  opinion 
as  to  which  side  of  a  leather  belt  should  be  next  to  the  pulleys. 
The  totally  uniformed  person  would  put  the  rough  or  flesh  side 
next  to  the  pulleys,  and  the  hard,  smooth  or  grain  side  out.  It 
is  the  more  natural  way  because  the  hard,  smooth  side  is  the  better 


Fig.  49 

looking.  Whichever  side  is  used,  that  same  side  should  be  in 
contact  with  all  the  pulleys  over  which  the  belt  runs.  If  the  flesh 
side  is  next  to  the  pulleys  it  should  have  a  coat  of  currier's  dubbing 
and  several  coats  of  boiled  linseed  oil  every  year.  The  grain  or 
hair  side  should  have  castor  oil  or  neatsfoot  oil  from  time  to  time 
to  keep  it  pliable. 

The  claim  is  made  that  a  belt  is  weakened  when  the  grain  side 
is  next  to  the  pulleys  because  the  natural  growth  of  the  hide  is 
being  worked  against.  Others  argue  that  the  flesh  side  stretches 
easier  and  should  be  on  the  outside  where  the  greatest  length  of 
belt  is.  The  more  common  and  probably  the  best  practice  is  the 
former  method,  i.  e.,  to  have  the  grain  or  smooth  side  against  the 
pulleys.  It  is  certain  that  there  is  a  better  contact  between  belt 
and  pulleys  this  way  and  more  horse-power  is  obtained. 


BELTING  66 

Rubber  belting  should  be  applied  with  the  seam  side  away  from 
the  pulley.  Where  a  belt  is  spliced  with  glue,  there  is  also  a  differ- 
ence of  opinion  as  to  application.  It  is  generally  assumed,  however, 
that  the  end  of  the  outside  lap  should  point  in  the  opposite 
direction  from  the  belt  motion,  to  prevent  the  air  resistance  from 
opening  the  splices.  This  rule  applies  to  both  leather  and  rubber 
belting. 


Fig.  50 

Where  belts  run  in  a  position  more  nearly  horizontal  than 
vertical,  there  is  a  sag  between  the  pulleys.  The  sag  in  the  lower 
half  of  the  belt  tends  to  decrease  the  amount  of  belt  that  actually 
would  touch  the  pulleys  were  the  belt  in  a  straight  line  between 
them.  The  amount  of  pulley  in  contact  with  the  belt  is  called  the 
arc  of  contact.  The  sagging  at  the  tops  tends  to  increase  the  arc 
of  contact  and,  as  the  horse-power  is  increased  by  adding  to  the 
contact  distance  between  pulleys  and  belt,  the  direction  of  the 
belt  should  be  such  that  the  sagging  at  the  bottom  will  be  decreased 
or  that  at  the  top  increased,  or  both.  Thus  a  rule  for  this  could 
be  stated  as  follows:  The  direction  of  the  belt  should  be  from  the 
top  of  the  driving  pulley.  See  Fig.  49  for  the  right  and  wrong 
methods  of  drive. 


66 


SCHOOL  SHOP  MAINTENANCE 


A 


PULLEY  SIDE  ^ 
Fig.  51 


62.  Joining   Belts. —  In   lacing   belts   observe   the   following 
rules:    For  belts  from  I"  to  3"  wide  make  holes  from  Y%   to  }/<£  from 
sides,  and  for  those  from  3"  to  10"  wide  make  holes  from  Y^'  to 
( c_1     %"  from  sides  (not  ends).    Always  have 

the  ends  of  the  belt  square  with  the  sides, 
Fig.  50.  Use  an  oval  punch,  making  the 
long  way  of  the  hole  parallel  to  the  long 
way  of  the  belt.  Do  not  make  holes  in 
rubber  or  canvas  belt  with  a  punch  but 
use  an  awl  or  sharpened  nail.  Make  holes 

only  as  large  as  necessary  to  get  the  lacing  thru.     The  punch  cuts 

the  strands  of  the  material  but  the 

awl    wedges    an     opening     between 

them.    The  lacings   on  the  grain  or 

pulley  side  of    the   belt   should   run 

parallel  to  the  length  of  the  belt.    The 

grain  side,  the  side  commonly  applied 

to  the  pulley,  is  the  smooth,  hard 

looking  surface.     It  is  the  outside  or 

hair  side  of  the  hide.    Make  crossings 

of  lace  come  on  the  outside  of  the 

belt.     After  lacing  with   rawhide  or 

wire,  flatten  the  lacings  with  a  wooden 

or  rubber  faced  mallet.    Do  not  pull 

the  lacings  tight  on  one  end  of  the 

joint  until   the  other  end  has  been 

brought    together    with    laces.     Use 

pliers  in  pulling  lacing.    Fasten  the 

ends  of  laces  by  pulling  them  thru  a 

small  hole  and  cutting  a  slit  on  each 

edge  of  the  lacing  close  to  the  belt. 

See  A,  Fig.  51.     These  slits  or  ears 

will  spread  out  on  either  side  of  belt  close  to  the  hole  and  prevent 

the  end  of  the  lacing  from  coming  thru. 

63.  Lacing  2"  to  4"  Belt  with  Rawhide. —  Use  method  shown  in 


\Tr~~ 


Fig.  52 


BELTING 


67 


Figs.  52  or  53.  If  the  method  illustrated  in  Fig.  52  is  used  and 
the  number  of  holes  in  each  end  is  odd,  start  the  lace  by  putting 
it  up  thru  3  and  8  referring  to  the  holes  numbered  on  A,  Fig.  52, 
from  the  grain  on  the  inside  of  the  belt.  The  end  that  came  thru 


Fig.  53 


Fig.  54 


3  is  then  crossed  over  and  inserted  back  thru  hole  8  and  up  thru 
3  again,  then  down  thru  9,  up  thru  2,  down  10,  up  thru  1,  down 
thru  10,  up  1,  down  9,  up  2,  and  finally  down  8.  It  is  then  fas- 
tened thru  hole  12  by  slitting.  The  other  end,  which  came  up 
thru  8,  goes  down  4,  up  7,  etc. 
and  finally  goes  down  3  and  is 
fastened  in  hole  1 1  similar  to  the 
other  end.  If  method  in  Fig.  53 
is  used,  start  by  putting  the  lace 
thru  hole  1  from  the  outside  and 
proceed  as  shown  by  arrows  in  the 
sketch.  For  simplicity  the  lace  is 
shown  by  one  line  only.  Finish 


Fig.  55 


by  putting  the  ends  thru  holes  F  and  slitting  as  shown  in  A .   Fig.  51. 
For  light  work  on  large  pulleys  use  single  butt  lacing  method 
shown  in  A  and  B,  Fig.  52. 


68 


SCHOOL  SHOP  MAINTENANCE 


64.  Other  Rawhide  Laces. —  Figs.  56,  57,  and  58  show  three 
other  common  methods  of  lacing  belts  with  leather.  In  each 
illustration  S  indicates  the  point  where  the  lace  is  started,  and 
F  the  point  where  it  is  fastened.  The  illustrations  suggest  the 


DOUBLE 
STRAIGHT 


Fig.  56 

steps  in  the  process  of  lacing.  One  half  of  the  lace  is  completed 
first;  then  the  lacing  is  brought  across  to  the  other  half  and 
finally  back  to  the  center,  where  it  is  fastened  as  suggested  in 
Section  63.  Care  must  be  taken  to  start  the  work  in  such  a  way 
that  the  strands  fall  parallel  to  the  direction  of  the  belt  on  the 
pulley  side  and  that  all  angular  strands  come  on  the  opposite 
side. 


M 


f4 


65.  Heavy  Work  on  Large  Pulleys. — Use  butt  lacing  methods 
in  Figs.  54  and  58.  In  Fig.  54  start  the  lace  in  hole  1.  The  arrows 
and  numbers  show  the  steps  to  take  with  the  lace.  Put  the  ends 
thru  hole  22  and  slit.  In  Fig.  55,  start  by  putting  the  lace  up  thru 


BELTING 


69 


holes  1  and  2  from  pulley  side.  Put  the  end,  that  came  thru  2, 
down  3  and  across  underneath  belt  and  up  thru  4.  Repeat  this 
operation  clear  across  that  half  of  the  belt.  Do  the  same  on  the 
opposite  half  with  the  other  end.  When  the  edge  of  the  belt  has 
been  reached,  work  back  the  same  way  but  putting  the  lace  also 
thru  holes  in  rows  A -B  and  C-D  as  you  do  so.  This  will  give  a 
double  lacing  across  ends  of  belt  and  a  single  lacing  thru  holes 
in  rows  A-B  and  C-D.  Fasten  the  ends  in  usual  method  in  T  and  T. 


PULLEY  SIDE 


Fig.  58 


Rubber  and  canvas  belts,  doing  heavy  duty  on  large  pulleys, 
should  be  laced  with  method  shown  in  Fig.  58.  For  lacing  by  this 
method  see  previous  paragraph.  For  small  pulleys  use  double 
hinge  method  in  Fig.  59.  In  this  method,  the  lace  should  be 
started  by  putting  it  down  thru  hole  1  from  the  top  and  by  bring- 
ing it  up  between  the  ends  of  the  belt  at  point  A.  Put  it  down 
thru  2,  up  between  ends  again  and  down  3.  Now  up  between  ends, 
down  4,  up  between  ends  and  down  5.  Continue  across  the  belt 
similarly.  Tie  one  end  by  putting  it  down  thru  hole  B  and  up 
thru  1  and  slitting  it  close  to  1.  Tie  the  other  end  likewise  at 
hole  C.  Dotted  lines,  in  drawing,  show  lacing  on  under  or  pulley 
side  of  the  belt.  Full  lines  show  it  on  the  top. 


70 


SCHOOL  SHOP  MAINTENANCE 


66.  Lacing  with  Wire. — In  using  wire,  follow  directions  on 
the  box  it  comes  in.  There  are  five  sizes  of  wire  and  the  size  of 
wire  to  use  will  depend  upon  the  width  and  thickness  of  the  belt. 

Belts  should  not  be  laced  with  wire  if 
they  are  to  be  shifted  by  hand  as  the 
ends  of  wire  will  almost  surely  tear 
the  flesh  of  the  operator.  Where  a 
belt,  more  than  four  inches  wide,  is  to 
be  laced  with  wire,  it  is  a  good  plan 
to  have  the  wire  in  two  shorter  lengths 
rather  than  one  long  one.  The  advan- 
tage is,  that  in  case  the  wire  breaks  in 
one  place,  the  belt  will  still  be  held 
in  place  by  the  good  wire  and  the 
time  required  to  repair  the  belt  will 
be  less.  In  leather  belts,  some  prefer 
to  cut  a  small  groove  from  awl  hole 


Fig.  59 


to  edge  of  joint  on  the  pulley  side  for  the  wire  to  lie  in.    This  will 
lessen  the  wear  somewhat.    In  any  case  the  wire  should  be  pounded 


Fig.  60 

flat  with  a  mallet.     This  groove  can  be  made  with  a  knife  or  a 
veining  tool  but  should  be  shallow.     The  holes  for  the  wire  can 


BELTING 


71 


be  made  with  an  awl  or  finishing  nail  ground  sharp,  but  should  be 
no  larger  than  absolutely  necessary.    They  should  be  about  Y% 
from  the  ends  of  the  belt  and  Y%   apart  for  a  4"  to  6"  belt.    In  lay- 


HOOK 


SECTION  ON  A-B 


Fig.  61 

ing  out  holes,  be  careful  to  get  them  exactly  opposite  each  other 
on  each  end  of  the  belt.  Always  have  the  ends  of  the  belt  square 
with  the  sides.  Use  a  square.  Do  not  guess.  See  Fig.  50.  Noth- 
ing will  get  a  belt  out  of  shape  more  quickly  than  having  joined 
ends  out  of  square. 

Use  the  method  shown  in  Fig.  60.     Start  in  hole  4  and  take 
steps  in  order  of  numbers  and  in  direction  of  arrows. 

67.  Patent  Fasteners. — The  patent  fasteners  shown  in  Fig. 
61  are  in  common  use  now  and  are  put  into  a  belt  with  a  small 
machine.  One  style  of  machine  is 
called  "The  Clipper."  This  is  a 
very  good  way  of  fastening  a  belt 
for  small  or  large  pulleys.  It  makes 
a  hinge  joint  and  the  holes  are  not 
in  line,  thereby  not  causing  the  belt  to  break  off  as  quickly  as  in 
some  styles  where  the  holes  are  in  line.  A  stiff  rawhide  pin  is  in- 
serted thru  the  loops  of  wire. 

Another  kind  of  patent  fastener  is  that  in  which  a  coil  of  wire 
is  run  thru  the  ends  of  the  belt  with  a  machine  leaving  loops  thru 


Fig.  62 


72 


SCHOOL  SHOP  MAINTENANCE 


which  a  rawhide  pin  is  inserted;  this  fastener  is  similar  to  the  style 
shown  in  Fig.  61  except  that  the  holes  are  in  line  and,  because  of 
this,  the  belt  often  breaks  off  in  a  line  thru  the  holes  whereas,  if 
they  are  zigzagged,  this  seldom  happens. 


BLAKE'S  HOOKS 
Fig.  63 


Belt  hooks  of  the  style  shown  in  A,  Fig.  62  are  only  good  for 
quick  repair  jobs.  They  are  put  thru  punch  holes  from  the  out- 
side of  the  belt  so  that  the  points  run  against  the  pulley.  They 
are  hammered  flat  with  a  mallet.  They  should  ba  no  farther  apart 


Fig.  64 

than  an  inch.    The  style  of  hook,  shown  in  B,  Fig.  62,  is  also  for 
hurry  up  jobs  and  can  not  be  highly  recommended. 

The  Alligator  Steel  Lacing,  similar  in  principle  to  the  style  in 


BELTING  73 

Fig.  61  is  one  of  the  best.  In  place  of  wire  hooks  a  perforated 
steel  plate  with  loops  is  clinched  to  the  ends  of  the  belt  and  a 
rawhide  pin  is  inserted. 

Blake's  Belt  Hooks,  A,  Fig.  63,  are  becoming  quite  generally 
used.  The  ends  of  the  belt  are  squared  and  clamped  together 
against  a  block  of  wood  in  a  vise,  Fig.  64.  A  slit  is  made  with  a 
carpenter's  chisel  of  the  proper  width  and  ground  to  a  long  bevel, 
or,  better  yet,  with  a  piece  of  Y^'  or  %"  band-saw  like  A ,  Fig.  64. 
This  should  be  ground  sharp  and  tempered.  Both  ends  of  belt 


•LENGTH  OF  5PUCL 
Fig.  65 

are  cut  at  once  as  shown  in  Fig.  64.  The  hooks  are  then  inserted 
as  shown  in  B,  Fig.  63.  The  belt,  when  completed,  will  look  like 
C,  Fig.  63. 

68.  Cemented  Splices. — A  cemented  splice  is  the  most 
satisfactory  way  of  joining  leather  belts.  The  ends  should  be 
squared  carefully  and  tacked  to  a  board  with  two  small  nails, 
Fig.  65.  On  the  board,  at  the  proper  distance  back  from  the  end, 
place  a  mark  showing  where  the  splice  is  to  end.  With  a  sharp 
plane,  pare  each  end  of  belt,  being  careful  to  have  laps  on  opposite 
sides  of  the  belt.  On  belts  from  1"  to  9"  wide  laps  from  5"  to  10" 
long.  On  wider  belts  make  laps  as  long  as  the  belt  is  wide. 

After  scarfing  the  ends,  place  the  belt  on  a  straight  line  drawn 


74  SCHOOL  SHOP  MAINTENANCE 

lengthwise  of  a  board,  as  in  Fig.  63,  or  against  a  thin  strip  of  wood 
tacked  on  the  board  as  a  straight  edge,  or  have  the  belt  line  up 
with  the  edge  of  the  board  at  the  edge.  Fit  laps  carefully  and  apply 
some  good  belt  cement  between  the  laps.  Knead  the  joint  well 
with  a  piece  of  a  broom  stick  used  like  a  rolling  pin.  Over  the 
joint,  lay  a  piece  of  board  and  clamp  the  two  boards  together 
tight.  Leave  them  thus  for  24  hours  to  allow  the  glue  to  thoroly 
set.  A  good  glue  can  be  made  by  heating  a  half  ounce  of  white 
lead  with  a  half  pound  of  good  white  glue  in  a  double  boiler  or 


JOINT 
MARK 


Fig.  66 

glue-pot.  Stir  this  mixture  constantly  until  a  thick  paste  is  ob- 
tained. When  it  is  to  be  used  it  should  be  made  into  a  thin  paste 
with  grain  alcohol  and,  if  possible,  warmed  when  applied. 

Rubber  belts  are  spliced  by  making  laps  as  in  leather  belts  only 
that  rubber  cement  is  used.  Apply  several  coats,  allowing  each 
to  dry  for  several  minutes  before  putting  on  the  next  coat.  The 
joints  should  be  clamped  tight,  and  when  dry  should  be  further 
re-inforced  by  a  few  copper  rivets.  The  laps  should  be  the  same 
thickness  as  the  rest  of  the  belt  whether  in  leather  or  rubber  belts. 
Pound  and  roll  the  splice  to  get  all  air  pockets  out.  Warming  the 
belt  and  boards  will  improve  conditions,  particularly  if  it  is  neces- 
sary to  make  the  splice  in  a  cold  place. 


BELTING  75 

69.  Don'ts. — Do  not  forget  to  square  ends  of  belt. 

Do  not  punch  larger  holes  or  use  larger  laces  than  necessary. 

Do  not  use  rosin. 

Do  not  become  too  lazy  to  gather  interest  from  your  investment 
in  a  belt  by  keeping  it  pliable  and  free  from  dirt  and  mineral  oils. 

Do  not  use  a  style  of  lacing  like  that  in  A,  Fig.  60  if  a  binder 
pulley  is  to  be  used.  This  is  a  fine  way  of  lacing  a  belt  because 
none  of  the  belt  is  cut  away  by  belt  holes  but  the  method  of  join- 
ing leaves  a  ridge  on  the  outside  of  the  belt  which  does  not  allow 
the  belt  to  work  well  with  a  binder  pulley.  In  this  case,  the  hinge 
lace  method  in  Fig.  59  or  the  Alligator  Steel  Lacing  would  be  more 
suitable. 

70.  To  Find  the  Horse-Power  Which  a  Belt  Will  Transmit. — 
Multiply  the  width  of  belt  by  diameter  of  driven  pulley  in  inches  and 
multiply  this  product  by  R.  P.  M.  of  driven  pulley.    Then  divide  this 
final  product  by  constant  2,750,  and  the  quotient  will  be  the  horse- 
power. 

Example:  What  horse-power  will  a  12"  belt  transmit  on  a  36" 
pulley  running  200  R.  P.  M.? 

Answer:  12  x  36  =432,  and  432  x  200  =  86,400,  86,400  divided 
by  2,750  =31.4  H.  P.  transmitted. 

71.  To  Find  Width  of  Belt  Required  for  a  Given  Horse-Power. 
— Multiply  the  horse-power  by  the  constant  2,750,  then  multiply  the 
diameter  of  driven  pulley  by  the  number  of  its  revolutions,  and  divide 
the  first  product  by  the  latter,  and  the  quotient  will  be  the  width  of 
belt  required. 

Example:  What  width  of  belt  will  be  necessary  to  transmit  20 
horse-power  over  a  30"  pulley  running  200  R.  P.  M.? 

Answer:  20  x  2,750=55,000  and  30  x  200=6,000,  55,000 
divide  by  6,000  =%"  width  of  belt  required. 

72.  With  Horse-Power  and  Width  of  Belt  Given,  Find  the 
Diameter  of  Driven  Pulley  Required.— .M ultiply  the  horse-power  by 
constant  2,750,  then  multiply  revolutions  of  pulley  by  width  of  belt 
and  divide  the  first  product  by  the  latter.     The  quotient  will  be  the 
diameter  needed. 


76  SCHOOL  SHOP  MAINTENANCE 

Example:  What  should  be  the  diameter  of  driven  pulley  at  200 
R.  P.  M.  to  transmit  10  horse-power  with  a  5"  belt? 

Answer:  10  x  2,750=27,500  and  200  x  5=1,000.  27,500 
divided  by  1,000=27%"  dia.  of  pulley. 

73.  To  Find  the  Length  of  Belt  Wanted. — Add  the  diameters  of 
both  pulleys  together,  divide  by  2  and  multiply  the  quotient  by  3.14. 
Add  this  product  to  twice  the  distance  between  the  centers  of  shafts  in 
inches  and  the  sum  will  be  the  length  of  belt  required. 

Example:  The  diameter  of  a  large  pulley  is  36"  and  the  diameter 
of  a  small  pulley  is  14".  Their  centers  are  12  ft.  apart.  What  length 
of  belt  is  needed? 

Answer:  36  plus  14  =50,  50  divided  by  2  =25,  25  x  3.14  =78.50, 
2  x  12  ft.  =288  inches.  288  inches  plus  78.50  inches  =366.5  inches 
or  30  ft.  6%  inches. 

74.  To  Find  the  Horse-Power  of  a  Driving  Pulley. — Multi- 
ply the  circumference  of  the  pulley  by  revolutions  and  multiply  this 
product  by  width  of  belt.    Divide  the  final  product  by  600.    Circum- 
ference =  dia.  in  inches  x  3.1416. 

Example:  What  is  the  horse- power  of  an  18"  pulley  making 
160  R.  P.  M.  with  a  6"  belt. 

Answer:  Circumference  =  18  x  3.1416  =56.55  and  56.5  x!60  = 
9,048,  9,048  x  6=54,288  and  54,288  divided  by  600=9.04,  the 
horse-power  wanted. 


CHAPTER  IX 

BABBITTING 

75.  Babbitt  Metal.— The  term  "babbitt"  comes  from  the 
name  of  the  inventor,  Isaac  Babbitt,  who  developed  the  recessed 
box  with  the  soft  metal  lining  for  machinery  bearings.  Babbitting 
means  the  pouring  of  babbitt  metal  into  a  box,  thereby  making  a 
bearing  for  the  shaft  that  runs  in  the  box. 

The  formula  for  the  original  babbitt  has  been  lost,  but  it 
probably  consisted  of  90  parts  tin,  3.7  parts  copper  and  6.3  parts 
of  antimony.  The  high  cost  of  tin,  however,  makes  it  expensive 
and  many  alloys  of  varying  compositions  have  been  put  on  the 
market  as  a  substitute,  and  many  of  them  named  "babbitt". 
Other  compositions  having  in  them  lead  or  zinc  have  become 
common.  White  metal  alloys  have  several  advantages  over  others. 
They  are  easily  melted  in  an  iron  ladle  over  bunsen  burners  or 
blow  torches,  or  in  a  forge.  Bearings  from  them  may  be  made  with 
practically  no  special  tools  and  the  time  required  to  run  a  bearing 
is  not  long.  They  have  good  anti-frictional  qualities  and  wear 
well.  When  badly  worn,  they  are  easily  chipped  out  and  replaced. 

The  composition  of  the  metal  should  depend  upon  the  purpose 
for  which  it  is  to  be  used.  For  high  pressure  bearings  at  high  or 
fast  speed,  an  alloy  called  Babbitt  Metal  Best,  and  having  the 
composition  stated  in  the  paragraph  above,  is  very  good.  For 
medium  pressure  and  medium  speed,  a  metal  containing  14.33 
parts  tin,  17.73  parts  of  antimony  and  67.89  parts  of  lead  will 
be  very  serviceable  and  is  cheaper  than  the  former.  An  alloy, 
having  this  proportion,  is  on  the  market  and  is  called  Graphite 
Bearing  Metal.  It  has  no  graphite  in  it,  however. 

For  shaftings,  which  ordinarily  run  at  comparatively  slow 
speeds,  Anti-friction  Metal  is  good  and  has  a  composition  of  88.32 
parts  lead  and  11.68  parts  antimony. 

77  •  - 


78  SCHOOL   SHOP  MAINTENANCE 

The  above  proportions  are  the  findings  of  an  analysis  of  bearing 
metals  (about  50  in  number)  made  by  The  Pennsylvania  Railroad 
Co.  at  their  laboratory  at  Altoona,  Pa. 

76.  Preparing  to  Pour  Babbitt  Metal. — If  the  job  be  that  of 
replacing  a  worn  bearing,  the  first  operation,  after  the  shaft  is 
out,  is  to  remove  the  old  babbitt.    This  can  be  done  with  a  cold 
chisel  by  chipping.     It  is  very  important  that  all  water  and  oil 
be  removed  from  the  recesses.     If  the  water  is  not  removed,  it 
will  suddenly  turn  into  steam  when  the  hot  metal  is  poured  upon 
the  box,  and,  increasing  in  volume  over  a  thousand  fold,  will 
"blow"  and  in  all  probability  cover  the  operator  with  molten 
metal,  doing  injury  to  the  flesh  and  eyes.     A  little  oil  will  not 
blow  but  it  will  blister  the  surface  of  the  metal  and  it  should, 
therefore,  be  removed.     Dirt,  left  in  the  recess,  will  also  cause 
trouble  for,  if  loose,  it  will  be  floated  by  the  heavy  metal  and  will 
make  a  pit  in  the  bearing  surface. 

Oil  and  water  can  be  removed  with  a  blow-torch,  if  one  is  at 
hand.  Another  way  to  remove  it  is  to  pour  gasoline  into  the  box 
and  burn  it.  Care  should  be  taken  to  keep  gasoline  away  from 
any  flame.  Sometimes  it  may  be  convenient  to  put  the  box  in  a 
forge  to  dry  it.  In  field  work,  when  nothing  else  is  handy,  a  fire  of 
wood  under  or  on  top  of  the  box  will  dry  it  out. 

77.  Alignment  of  the  Shaft. — When  it  is  time  to  align  the  shaft 
or  locate  it  properly  in  the  box,  it  is  better  to  use  a  mandrel  of  the 
same  size  or  a  trifle  larger,  for,  whether  the  shaft  or  a  mandrel 
is  used,  conditions  are  made  more  ideal  by  heating  the  box  or  the 
shaft  or  the  mandrel  and,  if  the  shaft  is  heated  or  hot  metal  is 
poured  on  it,  it  is  liable  to  be  warped,  sprung  and  thrown  out  of 
alignment.     This  will  cause  the  bearing  to  wear  out  quickly  or 
burn  out.     If  heated  with  a  blow-torch,  heat  will  not  be  evenly 
distributed  all  around  the  shaft  in  all  probability,  and  if  the  hot 
metal  is  poured  down  thru  an  oil  hole,  it  will  strike  in  one  place  on 
the  shaft  and  cause  it  to  expand  there  more  than  elsewhere.    The 
metal,  cooling  quickly  about  the  shaft  and  shrinking  tight  against 
it,  will  hold  it  tightly  in  this  form  (expanded  on  one  side)  until 


BABBITTING  79 

cool.  'Careful  testing  will  show  that  the  shaft  is  convexed  laterally 
at  the  point  where  the  molten  metal  struck  it.  The  amount  may 
be  small  but  the  uneveness  may  be  felt  if  the  shaft  is  turned  by 
hand,  and,  if  turned  by  power  at  fast  speeds  unsatisfactory  results 
will,  in  most  cases,  follow.  For  the  above  reasons,  if  several 
bearings  are  to  be  made,  it  is  better  to  use  a  mandrel.  A  mandrel 
can  be  easily  made  on  the  lathe  and  kept  for  this  purpose.  In 
an  emergency,  a  piece  of  pipe  of  the  right  size  and  wrapped  with 
paper  may  be  used. 

The  matter  of  aligning  cannot  be  treated  of,  except  in  a  general 
way,  for  seldom  are  conditions  twice  alike.  However,  there  ara  a 
few  considerations  which  should  have  careful  attention  when 
making  a  new  bearing:  For  instance,  consider  a  shaft  on  which  a 
circular  saw  runs.  It  is  important  that  the  shaft  or  arbor  be 
parallel  to  the  saw  table  when  the  latter  is  at  O  degrees  or  in  a 
horizontal  position.  If  the  saw  table  is  level  then  the  arbor  also 
should  be  level,  and  a  spirit  level  can  be  used  in  setting  the  mandrel 
in  place  for  babbitting.  It  is.  also  important  that  the  saw  rotate 
in  a  plane  parallel  to  the  fence  or  stock  guide  on  top  of  the  table. 
Again,  if  the  bearing  being  made  is  for  a  grindstone  shaft,  and 
the  frame  of  the  grindstone  is  fastened  to  the  floor  and  cannot  be 
easily  moved,  it  is  necessary  to  have  the  shaft  at  right  angles 
to  the  belt  which  drives  it;  otherwise  the  belt  will  not  stay  on  the 
pulley.  In  this  case  the  easiest  way  to  align  the  shaft  is  to  make 
the  distance  from  each  end  of  the  shaft  to  the  line  shaft  the  same. 
If  one  were  pouring  the  middle  bearing  of  an  overhead  line  shaft 
having  three  bearings,  he  would  wish  the  shaft  to  be  straight; 
if  not  supported  in  the  center,  the  weight  of  the  shaft  would  cause 
it  to  sag  there.  In  this  case  the  best  way  to  align  the  shaft  would 
be  with  straight  edge  and  level  as  explained  in  the  section  on 
shafting  (Page  18).  The  shaft  can  be  kept  from  sagging  in  the 
center  by  blocking  it  or  tying  it  up.  In  a  similar  way,  the  hori- 
zontal alignment  can  be  made,  i.  e.,  by  stretching  a  wire  horizon- 
tally opposite  the  center  of  the  shaft  at  precisely  the  same  distance 
from  the  shaft  at  each  end,  and  tying  the  centre  of  the  shaft  so 


80  SCHOOL  SHOP  MAINTENANCE 

that  it  measures  the  same  distance  to  the  wire  as  do  the  ends  of 
the  shaft. 

The  matter  of  aligning,  then,  is  one  to  be  considered  differently 
for  nearly  every  condition  under  which  a  bearing  is  poured  and 
calls  for  good  judgment  and  mechanical  sense.  Aligning  a  shaft 
for  a  grindstone  is  a  comparatively  simple  job  but  getting  a  crank 
shaft  for  a  gas  engine  aligned  properly  calls  for  considerable  skill. 
The  matter  of  holding  a  shaft  or  mandrel  in  its  place,  after  it  has 
been  aligned,  is  a  varying  problem  also,  but,  in  most  cases,  wood 
blocking  will  suffice  for  this  purpose.  In  any  case,  shafting  should 
be  substantially  fixed  so  that  it  will  not  move  after  much  time  has 
been  spent  in  'aligning  it  properly. 

78.  Preparing  the  Shaft. — The  next  step  is  to  prepare  the 
shaft  or  mandrel  so  that  it  will  leave  a  smooth  surface  on  the 
bearing  metal.  Some  mechanics  chalk  the  mandrel.  This  will 
do,  provided  the  mandrel  is  smooth  and  the  box  is  of  such  a  type 
as  to  allow  the  mandrel  to  be  heated  before  the  metal  is  poured. 
If  the  metal  is  poured  around  the  shaft  itself  and  there  is  objection 
to  heating  the  shaft,  as  there  well  might  be,  then  a  piece  of  good 
quality  writing  paper  wrapped  about  the  shaft  will  protect  the 
latter  and  leave  a  smooth  surface  on  the  bearing  metal,  and,  in 
case  the  mandrel  could  not  be  heated,  this  paper  acts  as  an  insulator 
and  prevents  the  metal  from  cooling  too  quickly,  leaving  blisters 
and  folds  on  the  bearing  surface.  It  also  prevents  the  contracting 
metal  from  gripping  the  shaft  quite  so  tightly  and  makes  subse- 
quent removal  of  shaft  and  scraping  of  the  bearing  less  difficult. 
The  paper  should  be  lapped  only  about  }/§'  and  glued  with  thin 
glue  or  shellac. 

After  gluing  the  paper,  plans  for  an  oil  groove  can  easily  be 
made  by  rubbing  clay  on  a  small  cord  or  wrapping  string  and 
putting  the  latter  around  the  shaft.  One  turn  around  the  shaft 
directly  under  the  oil  hole  in  the  box  should  first  be  made  and  a 
knot  tied.  Then  each  end  of  the  string  should  be  wound  spirally 
around  the  shaft  towards  an  end  and  in  such  a  direction  that  the 
turning  of  the  shaft  will  cause  the  oil  to  work  out  along  the  groove 


BABBITTING 


81 


that  is  to  be  left  by  the  cord.  That  is,  wind  each  end  in  the  direc- 
tion the  shaft  turns,  Fig.  67.  Make  only  one  to  three  turns  about 
the  shaft  with  each  end  and  go  no  nearer  the  end  of  the  bearing 
than  about  %*  and  fasten  the  string  there  by  wrapping  it  square 
around  the  shaft  once  and  tying  it.  This  method  can  perhaps  be 
more  easily  used  on  a  split  box  than  a  solid  one  but,  on  the  latter, 
it  can  be  used  by  gluing  the  paper  around  the  shaft  just  at  one  side 
of  the  box,  tying  the  string  around  it  there  and  finally  slipping  the 


Fig.  67 

paper  and  string  gently  into  place  in  the  box,  taking  care  that  the 
center  knot  on  the  string  lines  up  with  the  oil  hole  in  the  box. 

79.  Damming  up  the  Box. — The  next  step  is  that  of  damming 
up  the  box  so  that  the  hot  metal  will  not  run  out.  A  good  material 
for  this  purpose  is  clay.  It  should  be  no  wetter  than  necessary 
to  mold  properly,  else  steam  will  be  formed  and  a  "blow"  result. 
A  "blow"  means  the  scattering  of  the  hot  metal  by  the  formation 
of  steam.  If  a  number  of  bearings  are  to  be  poured  and  the 
material  is  to  be  used  for  damming  again  and  again,  putty  mixed 
with  asbestos  will  not  dry  out  like  clay,  and  requires  mixing  but 
once  each  time  bearings  are  to  be  poured.  Putty,  if  not  mixed  with 


82  SCHOOL  SHOP  MAINTENANCE 

the  asbestos,  will  get  very  soft  when  warmed  and  will  not  hold 
the  molten  metal  in  the  box. 

80.  Melting  the  Metal. — While  this  process  of  damming  is 
going  on,  the  babbitt  metal  can  be  melting.    The  melting  place 
should  be  as  close  to  the  pouring  place  as  possible  so  as  to  avoid 
the  cooling  of  the  metal  between  the  fire  and  the  box.     If  it  is 
necessary  to  carry  the  metal  some  distance,  it  will  require  heating 
to  a  little  higher  temperature  in  order  to  allow  for  the  cooling  that 
will  take  place  when  it  is  carried  to  the  place  of  pouring.    Enough 
should  be  melted  to  allow  plenty  for  filling  the  box  and  some  for 
a  possible  leakage.    Much  time  will  be  wasted  if  it  becomes  neces- 
sary to  chip  the  bearing  out  again  and  pour  over  because  there 
was  not  enough  metal  to  fill  the  box. 

It  is  a  common  fault  to  overheat  babbitt.  This  makes  it 
brittle  and  may  cause  a  loss  of  some  of  the  properties  thru  volatili- 
zation. It  should  not  become  so  hot  as  to  show  a  reddish  purple 
tinge  on  top  of  the  molten  metal.  It  should  have  a  yellowish  color. 
A  practical  test  that  can  be  relied  upon  is  that  of  inserting  a 
piece  of  white  pine  into  the  metal.  After  immersion  for  about 
three  seconds,  it  should  be  darkly  browned,  but  not  charred. 

81.  Pouring  the  Metal. — In  pouring,  it  is  important  that  there 
be  plenty  of  air  vents,  in  order  that  no  air  bubbles  form,  and  so  as 
to  allow  the  escape  of  steam.    In  case  there  is  only  one  oil  hole,  and 
that  one  is  being  used  to  pour  into,  air  vents  can  be  made  in  the 
clay  at  each  end  of  the  box  by  packing  the  clay  around  a  match 
or  nail  and  building  it  up  high  so  that  molten  metal  will  not  run 
away  and  make  it  difficult  to  fill  the  box.    Where  possible,  pieces 
of  cardboard,  carefully  fitted  around  the  shaft  at  the  end  of  the 
box  and  held  there  by  the  clay,  will  add  to  the  appearance  of  the 
ends  of  the  bearing  as  well  as  prevent  the  clay  from  drying  out 
so  quickly  and  forming  steam. 

There  are  two  types  of  boxes  in  common  use,  namely  open 
and  closed  boxes.  By  the  former  is  meant  a  box  in  two  halves 
split  thru  the  center  lengthwise.  The  two  halves  are  held  together 
by  set-screws  or  bolts.  Between  the  halves  are  shims.  Shims  are 


BABBITTING  83 

thin  pieces  of  brass  or  other  metal,  or  pieces  of  oiled  paper  or  card- 
board. Their  purpose  is  to  make  the  bearing  adjustable  for  wear. 
As  the  bearing  becomes  worn  layers  of  the  shimming  material 
may  be  taken  out,  allowing  the  halves  to  fit  closer  together  and 
thereby  taking  up  any  play  that  there  may  be  between  the  bearing 
and  the  shaft. 

The  closed  box  is  one  that  is  not  split  and  is  not  adjustable  for 
wear  except  by  a  new  pouring. 

Open  boxes  can  be  poured  in  two  ways,  namely,  pouring  each 
half  separately  or  pouring  both  at  once.  Fig.  67  shows  the  lower 
half  being  poured.  Notice  the  blocking  which  holds  the  shafting 
in  place.  On  each  end  of  the  box  are  pieces  of  cardboard,  B,  cut 
as  shown  in  Fig.  68.  Notice  the  slit  that  has  been  made  from  the 
edge  of  the  cardboard  to  the  hole  for  the  shaft.  By  springing  the 
cardboard,  it  can  be  easily  forced  around  the  shaft.  Against  the 
cardboard  is  packed  clay  to  keep  the  metal  from  running  out  of  the 
box.  Around  the  shaft  is  placed  a  thickness  of  paper  held  in  place 
by  pasting  the  edges  and  assisted  by  a  cord  which  has  been  rubbed 
with  clay  and  is  used  to  form  an  oil  groove.  Notice  that  it  is 
wound  spirally  and  in  the  direction  of  the  turning  of  the  shaft 
which  in  this  case  is  clock-wise.  The  metal  is  poured  into  the  lower 
half  until  it  is  full.  Heating  the  box  on  the  outside  will  assist  in 
making  a  smooth  surface  by  keeping  the  metal  from  cooling  too 
quickly.  This  can  be  done  with  a  blow  torch.  When 
the  metal  has  set  and  is  cool  enough  to  work,  that 
part  of  the  metal  which  rises  above  the  top  of  the  box 
is  cut  away  with  a  cold  chisel.  The  cutting  should  be 
done  lengthwise  of  the  shaft  and  care  taken  not  to  cut 
or  score  the  latter.  In  fact,  if  a  little  ridge  of  metal  is 
left  close  to  the  shaft  it  will  do  no  harm  and  can  be  scraped  off  later. 
Shims,  of  the  proper  size  and  shape  to  fit  the  flat  surfaces  of  metal 
on  each  side  of  the  box,  are  now  cut  and  put  in  place  and  the  upper 
half  is  fitted  over  the  lower  one.  These  shims  should  total  about 
J/g"  in  thickness.  The  upper  box  is  securely  fastened  and  the  ends 
are  banked  with  clay,  Fig.  69.  One  important  point  to  remember 


Ch 


84 


SCHOOL  SHOP  MAINTENANCE 


is  that  there  should  be  an  air  vent  or  two  for  steam  and  air.  If 
there  are  two  oil  holes  in  the  upper  half,  one  of  them  can  be  used 
for  pouring  and  the  other  for  an  air  vent.  If  there  is  only  one  hole 
then  a  vent  should  be  made  in  the  clay  at  the  end  of  the  box. 
In  Fig.  69,  nails  can  be  seen  at  the  end  of  the  box  about  which 
clay  was  packed.  When  the  nails  were  removed  vents  were  left. 
In  this  picture,  clay  can  also  be  seen  built  up  around  the  oil  hole 
to  facilitate  pouring. 


Fig.  69 

In  case  there  is  no  oil  hole  in  the  upper  half  of  the  box,  the  metal 
will  have  to  be  poured  in  the  end  of  the  box  as  shown  in  Fig.  70. 
A  port  is  also  made  here  by  building  up  with  clay.  If  the  box 
was  vertical  rather  than  horizontal,  it  would  be  necessary  to  pour 
it  at  the  end;  only,  in  this  case,  the  upper  end  of  the  box  would 
not  be  clayed  and  would  thus  serve  for  both  a  pouring  port  and  a 
vent.  Any  oil  holes  would  be  filled  with  clay. 

In  pouring  both  halves  at  once,  shims  are  placed  between  the 
halves,  as  explained  above,  together  with  a  piece  of  cardboard 
which  is  notched  as  shown  in  E,  Fig.  71  and  should  rest  against 
the  shaft.  The  total  thickness  of  the  shims  and  the  cardboard 


BABBITTING 


85 


should  be  a  trifle  more  than  yg .  The  notches  should  be  made 
twice  the  size  and  distance  apart  shown  in  the  drawing  for  the 
metal  must  run  thru  them  in  order  to  fill  the  lower  box,  and  if  too 
small  the  box  will  not  fill  easily;  whereas,  if  they  are  too  large, 
trouble  will  be  encountered  in  breaking  them  apart.  This  card- 
board is  to  make  separation  of  the  halves  easy.  The  halves  are 
broken  apart  by  striking  several  snappy  blows  with  the  cold  chisel 
at  the  parting  of  the  halves  after  the  shims  have  been  removed. 


Fig.  70 

82.  Scraping  the  Babbitt. — To  get  a  good  bearing  between 
the  metal  and  the  shaft,  the  metal  must  be  scraped.  There  are 
many  good  bearing  scrapers  on  the  market.  A  very  good  one  can 
be  made  out  of  a  half-round  wood  file  by  grinding  it  smooth  and 
then  forming  it  to  the  shape  shown  in,  D,  Fig.  71.  The  edges 
should  be  ground  and  whetted  sharp  as  shown  in  the  cross  section 
view,  C,  in  the  same  figure. 

The  first  operation,  in  fitting  the  bearing  to  the  shaft,  is  to  free 
the  corners  so  they  will  appear  like  spaces,  A,  Fig.  72.  This 
should  be  done  on  the  lower  half  and  will  prevent  a  possible 
pinching  of  the  shaft  at  the  corners.  The  shaft  should  be  free 


86 


SCHOOL  SHOP  MAINTENANCE 


for  a  distance  of  J4"  down  from  the  parting  on  the  lower  half  and 
an  equal  distance  up  on  the  upper  half.  After  freeing  the  corners, 
a  little  Prussian  blue,  or  lampblack  mixed  with  oil,  is  rubbed  on 


SECTION  ON  AB 


Fig.  71 

the  shaft  and  the  latter  is  carefully  lifted  to  its  place  in  the  bearing, 
given  several  turns  and  removed.  The  high  places  or  the  points 
in  the  bearing  that  touched  the  shaft  will  be  colored  and  the  other 
places  will  not  be.  By  taking  the  scraper  and  removing  a  slight 


Fig.  72 

bit  of  metal  from  these  high  places  a  more  complete  touching  of 
the  shaft  and  the  bearing  will  be  effected.  This  process  must  be 
repeated  a  number  of  times  until  approximately  75  per  cent  of 
the  bearing  touches  the  shaft.  Care  should  be  taken  not  to  get 


BABBITTING  87 

too  much  color  on  the  shaft  for  it  will  mark  the  low  places  as  well 
as  the  high.  Enough  color  will  generally  remain,  after  the  first 
application,  to  color  the  shaft  two  or  three  times  before  it  is  neces- 
sary to  put  more  on.  When  more  than  one  bearing  is  being  fitted 
for  the  same  shaft,  they  should  be  scraped  in  together,  i.  e.,  one 
bearing  should  not  be  completed  without  fitting  the  other,  for 
if  this  is  done  the  scraping  of  the  second  bearing  will  lower  the 
shaft  and  throw  it  out  of  alignment  with  the  first  no  matter  how 
carefully  it  may  have  been  fitted. 

When  the  lower  half  of  each  box  has  been  completed,  the  upper 
halves  are  put  in  place  with  no  shims  and  marked  by  turning  the 
shaft.  They  are  scraped  to  fit. 

The  shims  should  now  be  inserted  between  the  halves.  The 
thickness  of  the  shims  should  be  the  same  on  each  side  of  the  box. 
A  good  shim  stock  can  be  obtained  which  is  made  of  very  thin 
sheets  of  brass  lightly  soldered  together.  These  thin  sheets  can 
be  peeled  off  with  a  knife  making  possible  a  fine  adjustment  of 
the  bearings.  The  amount  of  shims  between  the  boxes  should  be 
such  that  the  shaft  will  be  free  to  rotate  when  the  boxes  are  fastened 
tight,  yet  there  should  be  no  noticeable  play  at  right  angles  to 
the. shaft ;  or,  in  other  words,  up-and-down  play.  In  case  of  a  heavy 
shaft,  this  can  only  be  determined  by  prying  the  shaft  up  with  a 
bar  or  stick.  A  fitting,  that  was  just  right  when  first  fitted,  will 
generally  be  found  to  be  loose  after  a  little  running  caused  by 
the  "fitting  in"  of  the  shaft,  and  some  of  the  shim  stock  will  have 
to  be  removed  to  do  away  with  this  play  of  the  shaft.  It  is  better 
to  remove  shims  after  a  little  running  than  to  fit  the  shaft  so  tight 
at  first  that  no  shims  will  necessarily  need  to  be  removed  later  on. 
If  the  shaft  is  fitted  too  tight  there  is  danger  of  burning  out  the 
bearing,  due  to  the  extra  friction.  A  new  bearing  should  be  kept 
especially  well  oiled  at  first. 


CHAPTER  X 

ADJUSTMENTS  OF  WOODWORKING  MACHINES 

83.  The  Circular  Saw. — Knowledge  of  the  care  that  should 
be  given  woodworking  machinery  and  the  proper  adjustments  will 
be  gained  more  from  experience  than  it  will  from  explanations 
found  in  texts. 

The  circular  saw  should  be  kept  well  oiled  on  the  arbor  bear- 
ings. The  sliding  table  and  tracks  should  be  kept  free  from  saw- 
dust and  gummed  oil.  Clean  them  frequently  with  kerosene  or 
gasoline,  and  rub  a  film  of  oil  on  the  bearing  surfaces  with  the 
fingers.  There  should  be  but  a  very  slight  bit  of  end  play  in  the 
arbors.  The  bearings  should  be  kept  as  tight  as  possible  without 
pinching  the  shaft.  The  screw  that  tilts  and  raises  or  lowers 
the  table  should  be  well  lubricated  and  kept  free  from  dirt. 

84.  The  Jointer. — Requires  a  fine  adjustment  of  knives  and 
table  in  order  to  do  good  work.    Assuming  that  the  table  and  knives 
are  entirely  out  of  adjustment,  the  first  step  in  an  attempt  to  put 
the  jointer  in  good  working  order  would  be  to  locate  one  knife 
in  its  place  in  the  cutter  head.     The  cutting  edge  of  the  knife 
should  project  from  the  head  about  %"  to  %%"  and  this  distance 
should  be  the  same  thruout  the  length  of  the  knife.    Tighten  the 
two  outside  or  end  nuts  as  much  as  possible  with  the  fingers,  and 
then  tap  the  knife  gently  with  a  mallet  or  block  of  wood  until 
the  exact  measurement  is  obtained. 

The  rear  table,  the  one  over  which  the  work  slides  last,  should 
now  be  so  adjusted  that  it  is  exactly  in  line  with  the  edge  of  the 
knife  at  its  highest  point  of  revolution.  This  is  important,  for  if 
too  high,  the  stock  will  hit  on  the  table  edge  and  be  stopped,  and 
if  too  low,  it  will  drop  to  the  rear  table  at  the  end  of  the  cut,  making 
an  uneven  edge.  To  get  the  rear  table  and  the  top  of  the  knife 
in  line,  a  try-square  or  straight  piece  of  smooth,  hard  wood  can 

88 


ADJUSTMENTS  OF  WOODWORKING  MACHINES  89 

be  laid  on  edge  on  the  rear  table  and  allowed  to  project  over  the 
knife.  The  head  can  be  slowly  turned  back  and  forth  now,  and 
the  rear  table  raised  or  lowered  until  the  knife  just  grazes  the 
straight  edge.  It  may  now  be  found  that  the  knife  comes  higher 
above  the  table  at  one  end  than  it  does  at  the  other.  This  means 
that  the  table  is  not  parallel  to  the  knife.  On  all  later  machines, 
there  is  an  adjustment  which  allows  the  level  of  the  table  to  be 
changed  by  raising  or  lowering  one  side  or  the  other.  This  should 
allow  the  table  to  line  up  with  the  knife.  If  the  tables  are  not 
adjustable  in  the  manner  indicated  above  then  the  only  alternative 
is  that  of  lining  the  knife  with  the  table.  The  author  has  seen 
tables  that  were  warped.  To  ascertain  if  a  table  is  warped,  put  a 
straight  edge  or  winding  stick  on  each  end  of  the  table  and  sight 
over  them.  Two  framing  squares  would  do  very  well  to  sight  over. 
This  warping  should  be  taken  out  by  means  of  the  sliding  shoe 
adjustment  or  similar  adjustment  under  each  corner  of  the  table. 

The  next  operation  is  that  of  getting  the  other  knife  to  line 
up  with  both  the  table  and  the  first  knife.  It  is  put  in  place 
precisely  as  was  the  first  knife,  care  being  taken  to  have  it  graze 
the  straight  edge,  which  is  laid  across  the  rear  table,  with  the  same 
friction  as  did  the  first  knife. 

The  final  adjustment  is  that  of  getting  the  front  table,  over 
which  the  work  first  slides,  in  line  with  the  two  knives  and  the 
rear  table.  It  is  adjusted  as  explained  for  the  rear  table.  It  can 
be  raised  to  the  same  height  as  the  rear  table  and,  by  sighting  or 
by  stretching  a  line,  one  can  determine  whether  they  are  lined  up 
lengthwise  or  not,  and  by  means  of  framing  squares  or  straight 
edges,  one  on  each  table,  the  side  alignment  of  the  two  tables  with 
one  another  can  be  determined.  While  lining  the  tables  with  one 
another,  the  cutter  head  should  be  so  turned  that  neither  knife 
is  at  the  top  of  the  revolution  and  in  the  way  of  sighting.  Of 
course  when  work  is  to  be  done  on  the  jointer,  the  front  table  is 
lowered  an  amount  equal  to  the  thickness  of  cut  that  is  to  be 
taken  from  the  stock.  This  adjustment  is  made  with  a  wheel  at 
the  end  of  the  table  or  on  the  side,  and  does  not  alter  the  condition 


90  SCHOOL  SHOP  MAINTENANCE 

that  should  exist  between  the  two  tables,  namely  that  they  should 
be  true  planes  parallel  to  each  other.  These  table  adjustments 
must  be  so  perfect  that  when  stock  passes  over  the  knives  it  should 
be  neither  raised  nor  lowered  even  a  trifle  as  it  passes  on  to  the  rear 
table.  Wherever  possible,  a  belt  from  a  jointer  should  pull  down 
on  the  cutter  head  pulley  so  that  there  will  be  the  least  up-and- 
down  motion  to  the  knives,  often  caused  by  loose  bearings  or  belt 
slap. 

85.  The  Surfacer. — The  attachment  for  grinding  surfacer  or 
planer  knives  can  not  be  adequately  described  here.  Reference  is 
made  to  one  that  fastens  on  the  planer  and  grinds  them  without 
removing  the  knives  from  the  machine.  A  finer  and  better  ad- 
justment can  be  obtained  this  way  than  by  the  old  method  of 
removing  the  knives  for  grinding,  and  necessitating  skill  and  much 
pains  in  getting  the  knives  properly  in  place  again. 

The  old  way,  spoken  of  above,  is  one  that  must  frequently  be 
used,  due  to  the  fact  that  all  equipments  do  not  include  the  grinding 
attachments.  For  adjusting  the  knives  after  they  have  been 
ground  and  jointed,  the  following  plan  is  followed:  Two  strips 
of  accurately  planed  hard  wood  are  placed  between  the  bed,  or 
table,  and  the  rollers.  These  strips  must  be  of  exactly  the  same 
thickness  and  the  thickness  must  be  known  by  the  operator.  The 
table  is  then  raised  to  such  a  position  that,  when  the  knives 
project  from  the  cutter  head  about  ^"  or  j^j"  they  will  Just  graze 
the  strips  of  wood.  At  the  same  time  the  pointer,  which  indicates 
the  thickness  of  stock  being  planed,  should  be  adjusted  so  that  it 
registers  the  thickness  that  the  strips  of  wood  measure.  The  nut 
at  each  end  of  the  knives  should  then  be  turned  tight  enough  to 
keep  the  blade  from  falling  out,  and  the  other  nuts  left  rather  loose. 
The  blades  should  be  left  out  of  the  cutter  head  a  slight  bit  more 
than  the  A"  and  gently  tapped  in  with  a  mallet  until  they  just 
graze  the  strips  of  wood  evenly  at  each  end.  If  the  other  nuts  are 
tightened  at  first,  too  hard  taps  are  required  to  make  the  knives 
move  in  the  head,  and  when  they  do  move  they  will,  in  all  probabil- 
ity move  so  much  as  to  throw  the  knives  farther  out  of  adjustment. 


ADJUSTMENTS  OF  WOODWORKING  MACHINES  91 

Great  care  should  be  taken,  however,  that  all  nuts  and  bolts  are 
left  tight  before  the  machine  is  ever  started,  or  serious  injuries  or 
damage  may  be  caused.  A  thoro  inspection  should  be  made  after 
it  is  thought  that  everything  is  in  perfect  shape. 

The  rollers  on  the  planer  or  surfacer  should  be  so  set  that  they 
will  keep  the  stock  moving  steadily  thru  the  machine,  yet  they 
should  be  no  tighter  than  necessary  to  get  this  result.  They  are 
adjusted  by  tension  springs  which  rnay  be  located  by  observation. 
Methods  of  tension  vary  on  different  makes  of  machines.  All 
bearings  should  be  well  oiled  at  all  times. 

86.  The    Mortiser. — The    mortiser    needs    more    care    than 
adjustment.     All  moving  parts  should  be  kept  clean  and  well 
oiled.    One  mistake,  often  made,  is  that  of  having  the  bits,  in  a 
hollow  chisel  mortiser,  drawn  up  into  the  chisel  so  far  that  when 
the  bit  is  revolved,  unnecessary  friction  is  caused  between  the  bit 
and  the  very  bottom  of  the  chisel,  and  the  latter  is  bulged  at  the 
bottom  and  the  temper  drawn.    This  is  not  necessary;  it  only  re- 
quires a  little  care  to  keep  the  bit  just  free  from  the  chisel  when  they 
are  tightened  in  place.     It  must  be  remembered  that  the  bit 
travels  fast  and  that  a  little  friction  between  the  chisel  and  the 
bit  will  soon  heat  the  chisel. 

87.  The  Band-Saw. — A  band-saw  is  a  simple  machine  to 
keep  in  shape,  yet  one  that  is  often  neglected.    On  all  machines 
there  is  an  adjustment  that  permits  of  lining  the  wheels  with  one 
another.    This  will,  in  most  cases,  be  found  on  the  upper  wheel. 
Observation  of  how  the  saw  travels  on  the  wheels  when  it  is  running 
free  of  the  guides,  will  tell  whether  the  wheels  are  properly  aligned. 
The  saw  should  center  both  wheels  when  unhindered  in  its  revolu- 
tion.   The  saw  guide  wheel  should  be  so  adjusted  that  it  does  not 
revolve  when  the  saw  is  running  idle  and  no  work  is  being  dons 
by  it.     However,  the  guide  wheel  should  be  as  close  to  the  saw 
as  is  possible  without  being  revolved  by  the  latter.     Under  such 
conditions,  one  is  assured  that  the  saw  is  taking  its  own  course 
over  the  wheels  and  will  run  true.    Of  course,  when  wood  is  pushed 
against  the  saw  to  be  cut,  the  wheel  should  run.    The  jaws  of  the 


92  SCHOOL  SHOP  MAINTENANCE 

guide  should  be  close  together  to  prevent  the  saw  from  twisting 
too  much,  yet  they  should  not  pinch  the  saw.  They  should  reach 
as  far  to  the  front  of  the  saw  as  possible  without  interfering  with 
the  set  of  the  teeth.  That  distance  will  be  almost,  but  not  quite, 
to  the  center  of  the  teeth  from  the  back  edge  of  the  saw. 

The  chief  causes  of  broken  band-saws  are  poor  tension  on  the 
saws,  dull  saws  which  will  not  do  their  duty,  and  poorly  brazed 
joints.  The  tension  should  be  such  that  the  saw  is  taut  and  free 
from  vibration,  and  yet  is  not  subjected  to  undue  strain.  Dull 
saws  mean  that  the  work  has  to  be  forced  against  them  so  hard 
in  order  to  be  cut  that  the  saw  is  under  a  strain  which  will  generally 
cause  trouble.  Thick  laps  or  brazes  will  cause  friction  between 
the  saw  guides  and  between  the  saw  and  the  kerf  in  the  wood, 
and  will  often  cause  the  blade  to  snap.  The  laps  should  be  filed 
until  they  are  of  the  same  thickness  as  the  rest  of  the  saw.  The 
saw  should  also  be  straight  where  it  is  brazed.  There  should  be 
enough  set  in  the  saw  to  allow  it  to  follow  a  curve. 

88.  The  Lathe.— The  lathe  should  be  kept  well  oiled  at  all 
times.  The  live  center  should  be  sharp,  so  that  heavy  blows  are 
not  required  to  sink  it  into  wood  the  proper  distance  for  revolving 
the  latter.  Drill  the  wood  for  the  center  and  make  saw  cuts  thru 
the  drill  hole  so  as  not  to  require  so  much  hammering  in  order  to 
sink  the  center  into  the  wood,  and  thus  save  the  bearing  from 
abuse.  The  bearings  should  be  kept  tight  at  all  times  to  insure 
a  minimum  of  vibration  both  endwise  and  up  and  down. 

As  a  suggestion  worthy  of  trial  a  sketch  is  shown  in  Fig.  73 
of  a  handy  grinder  that  can  be  made  in  the  school  shop.  It  is 
intended  for  use  on  the  lathe  for  grinding  edge  tools.  It  consists 
of  a  rraple  arbor  on  which  is  mounted  an  emery  wheel  of  the  size 
desired.  The  wheel  should  have  at  least  a  1"  face  for  edged  tools. 
A  keyway  is  made  in  the  lead  lining  to  the  arbor  hole  in  the  wheel 
and  also  in  the  arbor  and  a  wooden  key  is  driven  in.  A  collar  can 
also  be  made  of  wood  and  slipped  on  to  the  arbor,  tight  to  the  wheel, 
and  be  held  in  place  by  the  key.  One  end  of  the  arbor  can  be 
tapered  to  fit  the  opening  for  the  live  center  in  the  head-stock,  and 


ADJUSTMENTS  OF  WOODWORKING  MACHINES 


93 


the  other  end  made  to  fit  the  dead  center.  The  tool  rest  can  be 
used  as  a  guide  on  which  to  steady  the  tools.  A  good  saw  gummer 
can  be  made  by  mounting  similarly  on  a  longer  arbor  an  emery 
wheel  that  has  the  proper  shaped  rim  for  gumming.  Care  must  be 
taken  in  holding  the  saw  to  keep  it  from  binding  and  breaking  the 
emery  wheel,  possibly  to  the  discomfiture  of  the  operator. 

89.     Play  in  Bearings. — Bearings  on  the  saw,  jointer,  surfacer, 
lathes,  etc.  should  be  free  from  much  play  or  looseness.     There 


SECTION  ON  A-B 


TAPERED  TO 

FIT  IN 
HEAD  STOCK 

FITS  DEAD  CENTEI 
Fig.  73 

should  be  end  play  for  the  jointer  and  surfacer  heads  so  that  they 
can  work  back  and  forth  as  they  revolve  and  a  little  play  is  not 
objectionable  in  the  spindle  of  the  lathe,  as  friction  is  thereby 
reduced,  but  the  saw  should  have  the  least  end  play  possible, 
to  avoid  over-heating  the  bearings.  The  looseness  in  machines 
like  the  lathe,  saw,  and  small  machines  can  be  determined  by 
testing  with  the  hands,  but  on  larger  machines  like  the  12"  jointer 
or  the  surfacer,  it  will  probably  be  necessary  to  use  a  stick  of  wood 
as  a  lever  because  of  the  weight  to  be  lifted.  Otherwise,  one  might 
be  misled  into  thinking  the  bearings  were  tight  when  the  real 
difficulty  was  that  the  weight  made  it  impossible  to  detect  the 
looseness  without  a  lever. 

Between  the  halves  of  the  bearing  should  be  found  shims  of 
thin  material.    When  it  is  decided  that  a  bearing  is  loose,  these 


94  SCHOOL  SHOP  MAINTENANCE 

thin  pieces  of  shimming  stock  can  be  removed  until  the  play  is 
reduced.  The  amount  taken  from  each  side  of  the  bearing  should 
be  equal.  The  bearing  bolts  should  then  be  snugly  tightened. 
If  after  this,  it  is  found  that  the  bearings  are  too  tight,  some  of 
the  shimming  material  should  be  replaced,  for  it  is  not  a  good  plan 
to  make  the  bearings  free  on  the  shaft  by  loosening  the  bearing 
bolts.  They  should  be  tight  at  all  times  and  the  amount  of  shim- 
ming material  between  the  bearings  should  decide  the  play  of  the 
shaft. 

Bearings  on  some  makes  of  lathes  are  adjusted  with  special 
devices.  Instructions  for  adjusting  these  are  furnished  with  the 
machines.  The  end  play  in  saws  is  adjusted  in  different  ways,  the 
common  method  being  that  of  turning  a  collar  on  the  shaft.  This 
collar  can  be  locked  when  properly  adjusted. 


APPENDIX 

ORGANIZATION  OF  THE  PRECEDING  MATERIAL 
FOR  TEACHING  PURPOSES 

The  subject-matter  presented  in  the  preceding  pages  can  be 
used  as  a  basis  for  training  vocational  and  manual  arts  teachers 
who  may  be  responsible  for  the  planning  and  installing  of  their 
school  equipment  and  who  surely  are  expected  to  keep  it  in  good 
running  order.  Much  of  this  material  can  also  be  used  by  teachers 
in  instructing  students  in  vocational  classes  about  such  work  as 
saw  fitting,  machine  adjustments,  repair  of  belts,  etc. 

The  most  effective  use  of  this  subject-matter  would  be  that  of 
the  laboratory-class  method  where  much  supplementary  material, 
other  than  the  text,  might  be  used,  combined  with  reading  assign- 
ments and  class  discussion. 

The  plan  of  organization  to  be  suggested  in  the  remaining  few 
pages  is  ample  for  a  full  40  weeks'  course  of  six  to  nine  hours  of 
work  each  week,  and  even  then,  some  of  the  work  covered  would 
need  to  be  dealt  with  rather  superficially.  In  this  last  statement, 
reference  is  made  to  the  use  of  the  material  for  teacher-training 
purposes. 

The  order  of  topics,  as  given  in  the  preceding  pages,  is  not 
necessarily  the  best  order  in  which  to  present  the  matter  for 
instruction  purposes.  In  fact,  it  is  doubtful  if  the  student  should 
study  installation  and  shop  planning  problems  until  he  has  become 
familiar  with  the  machines  and  equipment  thru  maintenance 
work  on  them. 

The  following  plan  of  organization  is  for  teacher- training 
purposes  and  is  suggestive  only: — 

1.  Fitting  Edge  Tools — Application  on  the  regular  edge  tools  of  the 
shop. 

2.  Fitting  Saws — The  first  work  may  well  be  done  upon  strips  of  soft 
steel  as  indicated  in  the  text  so  that  students  get  actual  lay-outs 

95 


96  SCHOOL  SHOP  MAINTENANCE 

of  teeth  by  use  of  the  bevel,  protractor  and  scribe.  Saws,  badly 
out  of  form,  are  the  most  difficult  to  work  upon,  and  should  be 
given  to  the  students  last. 

3.  Belting — Short  pieces  of  belting  of  the  several  kinds  and  widths 
should  be  provided  so  that  the  various  methods  of  lacing  can  be 
practiced.     These  pieces  may  be  used  repeatedly,  and  when  the 
holes  become  badly  worn,  the  ends  of  the  pieces  may  be  cut  and 
new  holes  punched.     In  case  it  is  inconvenient  to  provide  pieces 
of  belting  or  in  case  it  is  wished  to  supplement  them,  methods  of 
lacing  may  be  practiced  by  means  of  the  Standard  Belt  Lacing 
•Card.  •  Holes  may  be  punched  in  the  proper  places  in  the  cards 
and  shoe  strings  or  cord  used  for  lacings.     Samples  of  various 
patent  lacings  may  be  procured  from  manufacturers. 

4.  Brazing  Band-Saws — Odd  pieces  of  broken  saws  may  be  used  until 
students  become  sufficiently  proficient  to  make  brazes  on  the  regu- 
lar shop  saws. 

5.  Adjustments — To  be  performed  on  the  regular  shop  equipment  if 
needed.     If  not  needed,  the  methods  for  making  the  adjustments 
should  at  least  be  demonstrated. 

6.  Babbitting  Bearings — Old  boxes  and  arbors  or  pieces  of  shafting, 
or  in  an  emergency,  pieces  of  pipe  filed  smooth,  may  be  used.    For 
the  first  lessons,   these  pieces  may  be  supported  by  wooden   V 
blocks  on  the  benches  or  table.     Later,   bearings  in  actual  use 
should  be  poured  and  fitted. 

7.  Power  Transmission  in  a  School  Shop — The  material  in  this  chapter 
can  be  assigned  for  study  and  class  discussion.     For  more  detailed 
study  and  reports,  the  references  given  in  the  bibliography  may  be 
assigned.     Examples  or  illustrations  of  various  hangers,  pulleys, 
etc.  may  be  provided  and  actual  problems  in  installation  may  well 
be  undertaken. 

8.  Motors  and  Currents — For  study  and  class  discussion  mainly.    More 
detailed  technical  information  may  be  obtained  by  use  of  the  refer- 
ences given. 

9.  Installation  of  Metalworking  Machines — For  study  and  class  dis- 
cussion.    Actual  work  in  installation   should   be  given  students  if 
possible. 

10.  Installation  of  Woodworking  Equipment — For  study,  class  discus- 
sion and  practice;  if  possible,  by  actual  installation  of  equipment. 

11.  Shop  Planning — Altho   no   space   is   given   to   treatment   of   this 
subject  as  a  separate  unit  in  the  preceding  pages,  yet  all  discus- 
sions on  installation  bear  directly  on  planning  the  shop.    An  actual 
problem  of  shop  planning  may  be  assumed  and  the  details  worked 


APPENDIX  97 

out  and  applied  in  the  form  of  drawings  on  large  sheets  of  cross- 
section  or  drawing  paper.  These  drawings  should  be  made  to 
scale,  %"  to  the  foot  being  a  good  scale  for  this  purpose.  Later, 
details  of  shafting,  pulley  and  belt  plans  may  be  drawn,  and,  if 
time  permits,  lists  of  equipment  giving  numbers,  sizes,  types, 
costs,  makes,  etc.  may  be  compiled.  In  attempting  the  shop- 
planning  problem,  as  indicated  here,  much  time  will  be  necessary, 
and  it  should  not  be  attempted  until  the  student  has  familiarized 
himself  with  the  material  on  installation  and  maintenance.  If 
actual  planning  problems  for  solving  can  be  obtained,  and  the 
installation  of  some  of  the  equipment  can  follow  the  planning,  then 
the  very  good  contact  between  theory  and  practice  should  result 
in  a  group  of  individuals  thoroly  prepared  to  solve  almost  any  school 
shop  installation  and  planning  problem. 


INDEX 

(NUMBERS  REFER  TO  PAGES) 


A 

Belting,  choosing  

61 

Adjusting 

clamp  for  lacing  

63 

band-saw  

.    .    .       91 

compared  

61 

circular-saw 

88 

direction  of 

65 

jointer   . 

...       88 

dressings  for  

62 

lathe 

92 

how  applied  to  pulleys 

64 

mortiser.    .    .    .    . 

...       91 

lacing  with  rawhide.    .    .    '.    , 

66 

surfacer  

/  .    .       90 

patent  fasteners  for  

71 

Aligning 

splicing      , 

66 

hangers      

.    .    .17,18 

stretching 

63 

pulleys  

.    .    .        20 

rules  for  finding  horse-power 

shafting  

.   17,18,78 

of    

75 

Bevel 

B 

Babbitt 

on  chisels  

42 

aligning  for  

.    .       79 

on  hand-saw  teeth  

51 

damming  box  for 

.    .       81 

on  plane  irons  

39 

formula  for   

...       77 

on  turning  tools  .    .    .    .  -,.   . 

42 

Blower 

31 

melting      

82 

Boxes 

oil  grooves  ri 

81 

•open  and  closed 

82 

pouring      

...       82 

preparing  to  pour.   .    . 
scraper  for      

...       78 
...       86 

damming  
Brazing  band-saws  
bunsen  burner  for    

81 
57 
60 

scraping  
shims  

...       85 
...       84 

use  of  blow  torch  for  .    .    „ 

60 

Band-saw 

using  tongs  for  ;    .  • 

59 

adjustments  to.    .    .    . 

...       91 

brazing  

...       57 

C 

filing  laps  on  

.   ..  .       57 

Chisels,  fitting      

42' 

fitting.    .    . 

.    .       52 

Circular  cross-cut  saws 

Bearings 

care  of   

88 

adjustments  to.    ... 

.   .   .       93 

gumming  

56 

babbitting. 

77 

shape  of  teeth  of 

56 

Belting 

speeds  of   

37 

care  of   

.   ,    .       62 

Circular  rip-saws 

cemented  snlices  in  . 

73 

filing  . 

54 

INDEX 


99 


Circular  rip-saws,  gage  for.    .    . 

55 

Hangers,  fastening  .  . 

18 

layout  of  teeth  

53 

formula  for  spacing  .    .    . 

16 

saw  clamp  for  .    

54 

for  aligning  shafting    .... 

19 

setting   

55 

types  and  selection  of  .    . 

15 

side-dressing  

55 

Horse-power 

template  for      

55 

for  woodworking  machines.    . 

37 

Couplings  for  shaft  

21 

of  belting  , 

75 

Cross-cut  saw,  fitting      .        .    . 

51 

required  for  group  drive.    .    . 

9 

Crown  in  saws                        % 

48 

transmitted  by  cold  rolled  steel 

shafting.    .    .   ,.,'„..    .    . 

11 

D 

turned  steel  shafting   .... 

13 

Draw  knife,  fitting  

43 

Drill  press,  installation  .... 

30 

I 

Individual   drive,    compared    to 

E 

others.    

7 

Emery  wheel,  speeds  of  .    . 

36 

Installation 

anvil 

31 

F 

blower               . 

31 

Forge  *-••'•   .    .    .  ...    . 

31 

drill  press                      .... 

30 

Formulas 

force 

31 

babbitt                                .  .    . 

77 

lathe 

30 

distance  apart  of  hangers  .    . 

16 

milling  machine 

30 

horse-power  of  shafting      .    . 

12 

planer    

28 

sizes  and  speeds  of  pulleys.    . 

22 

shaper    .    .'  .    ......... 

31 

woodworking  equipment.   .    . 

33 

G 

Gouges,  fitting  

44 

J 

Grinding,  plane  irons  ,   -.    .  .  .    .    ', 

40 

Jointer,  adjustments  to  .... 

88 

Group  drive,  compared  to  others  . 

7 

Jointer,  home-made  saw.    .    .    . 

49 

H 

Jointing  hand  saws  

49 

Hand  rip-saw 

K 

angle  of  teeth  .    .    ,    .  •  .    .1 

47 

Keyhole  saw  filing  .           ... 

52 

clamp  for  filing  

48 

how  to  file  

48 

L 

jointing 

49 

Lacing  belts 

setting   .    .    .    .  *  •  

49 

with  rawhide  

66 

side-dressing  .    .    ^  .    /  .    .    . 

50 

alligator  steel  lacing  

72 

Hangers  

Blake's  belt  hooks  

73 

alignment  with  taut  line.   .    . 

18 

cemented  splices  

73 

alignment  with  transit    

17 

clipper  lacing    

71 

distance  apart  and  where  placed 

16 

rubber  and  canvas  belts.    .    . 

69 

36173 


661942 


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